Fourth Walking Leg Research Articles

Mechanosensory pathways of scorpion pecten hair sensillae-Adjustment of body height and pecten position.

Scorpions' sensory abilities are intriguing, especially the rather enigmatic ventral comb-like chemo- and mechanosensory organs, the so-called pectines. Attached ventrally to the second mesosomal segment just posterior to the coxae of the fourth walking leg pair, the pectines consist of the lamellae, the fulcra, and a variable number of pecten teeth. The latter contain the bimodal peg sensillae, used for probing the substrate with regard to chemo- and mechanosensory cues simultaneously. In addition, the lamellae, the fulcra and the pecten teeth are equipped with pecten hair sensillae (PHS) to gather mechanosensory information. Previously, we have analyzed the neuronal pathway associated with the peg sensillae unraveling their somatotopic projection pattern in dedicated pecten neuropils. Little is known, however, regarding the projections of PHS within the scorpion nervous system. Behavioral and electrophysiological assays showed involvement of PHS in reflexive responses but how the information is integrated remains unresolved. Here, we unravel the innervation pattern of the mechanosensory pecten hair afferents in Mesobuthus eupeus and Euscorpius italicus. By using immunofluorescent labeling and injection of Neurobiotin tracer, we identify extensive arborizations of afferents, including (i) ventral neuropils, (ii) somatotopically organized multisegmental sensory tracts, (iii) contralateral branches via commissures, and (iv) direct ipsilateral innervation of walking leg neuromeres 3 and 4. Our results suggest that PHS function as sensors to elicit reflexive adjustment of body height and obstacle avoidance, mediating accurate pecten teeth alignment to guarantee functionality of pectines, which are involved in fundamental capacities like mating or navigation.

Structure of the pecten neuropil pathway and its innervation by bimodal peg afferents in two scorpion species.

The pectines of scorpions are comb-like structures, located ventrally behind the fourth walking legs and consisting of variable numbers of teeth, or pegs, which contain thousands of bimodal peg sensillae. The associated neuropils are situated ventrally in the synganglion, extending between the second and fourth walking leg neuromeres. While the general morphology is consistent among scorpions, taxon-specific differences in pecten and neuropil structure remain elusive but are crucial for a better understanding of chemosensory processing. We analysed two scorpion species (Mesobuthus eupeus and Heterometrus petersii) regarding their pecten neuropil anatomy and the respective peg afferent innervation with anterograde and lipophilic tracing experiments, combined with immunohistochemistry and confocal laser-scanning microscopy. The pecten neuropils consisted of three subcompartments: a posterior pecten neuropil, an anterior pecten neuropil and a hitherto unknown accessory pecten neuropil. These subregions exhibited taxon-specific variations with regard to compartmentalisation and structure. Most notable were structural differences in the anterior pecten neuropils that ranged from ovoid shape and strong fragmentation in Heterometrus petersii to elongated shape with little compartmentalisation in Mesobuthus eupeus. Labelling the afferents of distinct pegs revealed a topographic organisation of the bimodal projections along a medio-lateral axis. At the same time, all subregions along the posterior-anterior axis were innervated by a single peg’s afferents. The somatotopic projection pattern of bimodal sensillae appears to be common among arachnids, including scorpions. This includes the structure and organisation of the respective neuropils and the somatotopic projection patterns of chemosensory afferents. Nonetheless, the scorpion pecten pathway exhibits unique features, e.g. glomerular compartmentalisation superimposed on somatotopy, that are assumed to allow high resolution of substrate-borne chemical gradients.

The Eophreatoicus Nicholls, 1926 species flock from Kakadu and Arnhem Land, with a description of a new genus of Amphisopidae (Crustacea : Isopoda : Phreatoicidea).

We present descriptions of 28 new species of Amphisopidae from Arnhem Land and Kakadu National Park of Australia's Northern Territory. We identified five additional species that are not yet fully characterized and are not provided with formal species recognition. This is the first taxonomic treatment highlighting the high species richness within the Phreatoicidea that occur in Australia and likely elsewhere. We document each species fully with scanning electron and light micrographic images, diagnoses, detailed descriptions, keys to identification and justification of each species using parsimony analysis of their morphological and genetic characters. The distributional data show that all species, except for one, have microendemic distributions, with some sibling species occurring within a few kilometers of each other. Because of the age of this group of species, they appear to have spread throughout the region of the Arnhem sandstone plateau and then back-colonized the same habitats so that as many as three morphologically and genetically distinct species may co-occur syntopically. Our research has uncovered a new genus-level taxon of the family Amphisopidae, Kakadubeh gen. nov. This new genus is unlike Eophreatoicus, not only in its general appearance, but also in having an inferred reproductive strategy different from most of the other members of the family. While Eophreatoicus species have males that are much larger than the females and practice precopula, a form of pre-insemination mate guarding, males of the new species, Kakadubeh rangemyahwurd sp. nov., are much smaller than females. In addition, males of this species have a fourth walking leg that is not specialized for holding females, suggesting that they have a reproductive strategy that does not involve precopula of the form seen in Eophreatoicus and Eremisopus Wilson Keable, 2002a. Most of our research has been undertaken in Kakadu National Park, although recent collections have been made in Arnhem Land, yielding additional distinctive species. Given the size of unexplored territory around the Arnhem Plateau and the geographic frequency of discovering new species, we predict that the diversity of this group in the Northern Territory may be many more than the ~35 species described here. At this time, these microendemic isopods appear to be unthreatened by human activities, largely owing to the environmental protection afforded by Kakadu National Park and Arnhem Land, and their cryptic habits during the dry season. Because they are dependent on small springs of permanent groundwater, future changes in hydrology owing to water use and climate change, as well as invasive introduced species, may present risks to populations and species.

Primary processing neuropils associated with the malleoli of camel spiders (Arachnida, Solifugae): a re-evaluation of axonal pathways

BackgroundArachnids possess highly specialized and unorthodox sense organs, such as the unique pectines of Scorpiones and the malleoli of Solifugae. While the external morphology, numbers, and shapes of sensory organs are widely used in taxonomic studies, little is known about the internal anatomy of these organs and their associated processing neuropils in the central nervous system. Camel spiders (Solifugae) possess pedipalps and first walking legs heavily endowed with sensory structures, as well as conspicuous malleoli located ventrally on the proximal fourth walking legs. Malleoli are fan-shaped organs that contain tens of thousands of presumptive chemoreceptor neurons, but mechanoreceptive structures are absent.ResultsHere, we examine the organization of the synganglion based on microCT analysis, 3D reconstruction of serial paraffin sections, and backfill preparations to trace the malleolar pathway. The projection area of malleolar afferents is intriguingly located in the most anterior ventral nerve cord, located in between the pedipalpal neuromere hemispheres. However, malleolar axon bundles are separated by a thin soma layer that points to an anteriad projection of the fourth walking leg neuromere. A conspicuous projection neuron tract that may receive additional input from pedipalpal sensory organs connects the malleolar neuropil with the mushroom bodies in the protocerebrum.ConclusionArthropod chemosensory appendages or organs and primary processing neuropils are typically located in the same segment, which also holds true in Solifugae, although the malleolar neuropil is partially shifted towards the pedipalpal neuromere. A comparison of the malleoli in Solifugae and the pectines in Scorpiones, and of their primary processing neuropils, reveals certain similarities, while striking differences are also evident. Similarities include the ventral arrangement of peg-shaped sensory structures on the respective segmental appendage, exposing dense arrays of chemoreceptive sensilla, and projections to a primary processing neuropil with glomerular subdivision. Differences are, e.g., the lack of mechanoreceptive afferents and an associated processing neuropil.

The delineation of the fourth walking leg segment is temporally linked to posterior segmentation in the mite Archegozetes longisetosus (Acari: Oribatida, Trhypochthoniidae)

Acari (mites and ticks) lack external segmentation, with the only indication of segmentation being the appendages of the prosoma (chelicerae, pedipalps, and four pairs of walking legs). Acari also have a mode of development in which the formation of the fourth walking leg is suppressed until the nymphal stages, following a hexapodal larva. To determine the number of segments in the posterior body region (opisthosoma) of mites, and to also determine when the fourth walking leg segment is delineated during embryogenesis, we followed the development of segmentation in the oribatid mite Archegozetes longisetosus using time-lapse and scanning electron microscopy, as well as in situ hybridizations of the A. longisetosus orthologues of the segmentation genes engrailed and hedgehog. Our data show that A. longisetosus patterns only two opisthosomal segments, indicating a large degree of segmental fusion or loss. Also, we show that the formation of the fourth walking leg segment is temporally tied to opisthosomal segmentation, the first such observation in any arachnid.

A Novel Protein Acts as a Negative Regulator of Prophenoloxidase Activation and Melanization in the Freshwater Crayfish Pacifastacus leniusculus

Melanization is an important immune component of the innate immune system of invertebrates and is vital for defense as well as for wound healing. In most invertebrates melanin synthesis is achieved by the prophenoloxidase-activating system, a proteolytic cascade similar to vertebrate complement. Even though melanin formation is necessary for host defense in crustaceans and insects, the process needs to be tightly regulated because of the hazard to the animal of unwanted production of quinone intermediates and melanization in places where it is not suitable. In the present study we have identified a new melanization inhibition protein (MIP) from the hemolymph of the crayfish, Pacifastacus leniusculus. Crayfish MIP has a similar function as the insect MIP molecule we recently discovered in the beetle Tenebrio molitor but interestingly has a completely different sequence. Crayfish MIP as well as Tenebrio MIP do not affect phenoloxidase activity in itself but instead interfere with the melanization reaction from quinone compounds to melanin. Importantly, crayfish MIP in contrast to Tenebrio MIP contains a fibrinogen-like domain, most similar to the substrate recognition domain of vertebrate l-ficolins. Surprisingly, an Asp-rich region similar to that found in ficolins that is likely to be involved in Ca2+ binding is present in crayfish MIP. However, crayfish MIP did not show any hemagglutinating activity as is common for the vertebrate ficolins. A mutant form of MIP with a deletion lacking four Asp amino acids from the Asp-rich region lost most of its activity, implicating that this part of the protein is involved in regulating the prophenoloxidase activating cascade. Overall, a new negative regulator of melanization was identified in freshwater crayfish that shows interesting parallels with proteins (i.e. ficolins) involved in vertebrate immune response.

Unionicola (Wolcottatax) Weni N. Sp. and U. (Wolcottatax) Arcuatoides Vidrine (Acari: Unionicolidae) From Freshwater Mussels in China

Unionicola (Wolcottatax) weni n. sp. (Acari: Hydrachnidia: Unionicolidae) is described from freshwater mussels Arconaia lanceolata from Nanchang, Jiangxi Province, China. The new mite resembles U. fengchengensis Wen and Zhu, 1996, but it can be distinguished by the number of genital acetabula and the morphology of the tarsus of the fourth walking legs. Both species are readily distinguished from U. arcuata (Wolcott, 1898) and U. arcuatoides Vidrine, 1986 by the shape of the tarsal claws and the morphology of the walking legs. Unionicola arcuatoides, previously known only from Japan, is reported from Acuticosta chinensis from Nanchang, Jiangxi Province, China.

Unionicola (Coelaturicola) edwardsi n. sp. (Acari: Unionicolidae) from freshwater mussels in Angola, Africa

Unionicola (Coelaturicola) edwardsi n. sp. (Acari: Hydrachnidia: Unionicolidae) is described from freshwater mussels, Chambardia moutai (Dartevelle, 1939) (Unionoida: Iridinidae), from the Cunene River Basin, Provincia da Huila, Cape Longo, upper Onquenha River, Angola, Africa. The new species has unique and distinctive male genital field morphology. The species illustrates sexual dimorphism in the chaetotaxy of the first and fourth walking legs. It further extends our knowledge of host-specificity among the Unionicola. Also, new host and geographic records are reported for Unionicola (Mutelicola) blayi Gledhill and Vidrine, 2002, and U. (Coelaturicola) gledhilli Vidrine et al., 2007b.

Diverged and conserved aspects of heart formation in a spider

Heart development exhibits some striking similarities between vertebrates and arthropods, for example in both cases the heart develops as a linear tube from mesodermal cells. Furthermore, the underlying molecular pathways exhibit a significant number of similarities between vertebrates and the fruit fly Drosophila, suggesting a common origin of heart development in the last common ancestor of flies and vertebrates. However, there is hardly any molecular data from other animals. Here we show that many of the key genes are also active in heart development in the spider Cupiennius salei. Spiders belong to the chelicerates and are distantly related to insects with respect to the other arthropods. The tinman/Nkx2.5 ortholog is the first gene to be specifically expressed in the presumptive spider heart, like in flies and vertebrates. We also show that tinman is expressed in a similar way in the beetle Tribolium castaneum. Taken together this demonstrates that tinman has a conserved role in the specification of the arthropod heart. In addition, we analyzed the expression of other heart genes (decapentaplegic, Wnt5, H15, even-skipped, and Mef2 ) in Cupiennius. The expression of these genes suggests that the genetic pathway of heart development may be largely conserved among arthropods. However, a major difference is seen in the earlier expression of the even-skipped gene in the developing spider heart compared with Drosophila, implying that the role of even-skipped in heart formation might have changed during arthropod evolution. The most striking finding, however, is that in addition to the dorsal tissue of the fourth walking leg segment and the opisthosomal segments, we discovered tinman-expressing cells that arise from a position dorsal to the cephalic lobe and that contribute to the anterior dorsal vessel. In contrast to the posterior heart tissue, these cells do not express the other heart genes. The spider heart thus is composed of two distinct populations of cells.

Larval development and morphogenesis of the sea spider Pycnogonum litorale (Ström, 1762) and the tagmosis of the body of Pantopoda

Aspects of pantopod ontogeny have been known for a long time, but specific information is available for only a few species. Our account of the postembryonic development of Pycnogonum litorale is based on laboratory-reared individuals and SEM studies. We documented particularly all early developmental stages, with emphasis on morphogenetic changes of head structures and appendages. In P. litorale the protonymphal limbs, the chelicerae and two more uniramous legs, degenerate already during the larval phase; only the third one, the ovigers, reappears in male juveniles. Other Pantopoda vary in this aspect from retention of all three protonymphal appendages to their complete reduction, as in P. litorale. Accordingly, the two post-cheliceral larval appendages are separate legs in front of the walking legs in the adults, the ‘parapalps’ and the ‘ovigers’, but they do not occur in all pantopods. The scarcity of studies of the ontogeny of Pantopoda prevents us from a more conclusive picture, but our data are promising to state that additional such studies will increase the usability of ontogenetic data for a phylogenetic analysis of Pantopoda, the crown group of the Pycnogonida. We also discuss the phylogenetic implications of our data in the light of new information from Hox genes and developmental-biological data on body segmentation and tagmosis of the Chelicerata. These suggest the homology of chelicerae and antenn(ul)ae of other euarthropods. Accepting this, we conclude that the adult pycnogonid/pantopod head, the cephalosoma, corresponds to the euarthropod head and that the protonymph with three appendage-bearing segments may represent an even shorter, possibly phylogenetically older larval type than the euarthropod ‘head larva’ bearing four pairs of appendages. In further consequence, the fourth walking legs of Pycnogonida/Pantopoda should correspond to the first opisthosomal appendages, the chilaria, of euchelicerates. This implies that within Pycnogonida the post-prosomal region became compacted during evolution to a single leg-bearing segment plus a tubular end piece. Accordingly, neither the anterior nor the posterior functional boundaries of the walking-leg region correspond to the original tagma borders.

Limb regeneration following auto- or interspecies transplantation of crab limb tissues

Summary We conducted a series of experiments designed to investigate the regulation of regeneration following implantations of limb tissues in crabs. Autotransplantation (transplantation within the same crab) of the fourth walking leg tissues into claw stumps regenerated either a walking leglike limb, bifurcated limbs, a composite limb with claw and walking leg characteristics, or a normal claw. Interspecies experiments consisted of claw tissues fiom the crab Cancer productus transplanted into the autotomized stump of the fourth walking leg of Cancer gracilis. The resulting regenerates appeared as either a claw-like limb, a walking leg with a toothed dactyl, a walking leg with two dactyls and two pollexes, or a normal walking leg. Reciprocal interspecies transplants of donor walking leg tissues into host claw stumps were able to induce the regeneration of walking leg-like limbs. Most of the regenerates had characteristics of both host and donor limbs. Our results suggest that both donor and host cells participate in limb regeneration. In the host claw stumps that produced the bifurcations, we propose that two distal organizers were generated. The identity of the limb fields generated by the distal organizers may be dependent upon the cells adjacent to the distal organizers, such that varying interactions between the two limb fields in the host stumps resulted in the formation of a range of regenerate morphologies.

Homeotic Transformation of Crab Walking Leg into Claw by Autotransplantation of Claw Tissue.

Homeotic transformation is defined as transformation of one body part into the likeness of something else. By autotransplantation of crab claw tissue into the autotomized stump of the fourth walking leg, the stump can regenerate a complete claw. Frozen claw tissue, sham operation, or walking leg tissue had no such activity. Contralateral autotransplantation of claw tissue into the autotomized stump of the fourth walking leg can induce the regeneration of a claw with normal handedness. Most of the transformed claws combined features of the claw and the walking leg, suggesting that both host and donor tissues play a role in regeneration. Three possible mechanisms that might account for limb transformation are discussed. Simple intercalary regeneration does not explain all of the observations, but some regulatory events might be taking place during regeneration. Two other processes--secretion of some morphogen by the claw tissue and alteration in the expression of Hox genes--offer alternatives that might explain the results of this study.

Androgenic Gland and Secondary Sexual Characters in the Crayfish Procambarus Clarkii

Reversed spines are present on the third and fourth walking legs of adult males of Procambarus clarkii. The spines appear to be indispensable for normal mating. The presence of these spines is dependent upon the presence of the androgenic gland hormone. Ultrastructural observations on the androgenic glands as well as physiological experiments support this conclusion.

Synaptic connections between motor neurons and interneurons in the fourth thoracic ganglion of the crayfish, Procambarus clarkii

1. A new preparation of the thoracic nervous system of the crayfish, Procambarus clarkii, has been developed, in which it is possible to work with identified members of motor neuronal pools. 2. In such a preparation, it is possible to dissect all specific proximal motor nerves (protractor, retractor, anterior elevator, posterior elevator, and depressor). Motor neurons innervating the four proximal muscles of the fourth walking leg have been identified both physiologically and anatomically by staining the recorded motor neuron with Lucifer yellow through the microelectrode. 3. By the use of cobalt chloride, we have mapped the distribution of somata of all motor neurons within the fourth thoracic ganglion that innervate the different groups of muscles controlling the movement of the fourth walking leg. 4. Most motor neurons innervating the same muscle seem to be electrically coupled, except some depressor motor neurons. 5. Motor neurons innervating antagonist muscles are linked by inhibitory connections. These connections are reciprocal for protractor and retractor motor neurons but usually not reciprocal between elevator and depressor motor neurons. 6. Walking interneurons were identified as neurons without axons in any motor nerve, which modified the motor neuronal activity. Some of them have been injected with Lucifer yellow. 7. Some interneurons make synaptic connections only with antagonist motor neurons that control the movement of one joint. Probably their functional role is to reinforce or to limit the antagonism between each pair of antagonist motor neurons. 8. Other interneurons make synaptic connections with motor neurons innervating muscles controlling different leg joints. These interneurons may play a role in generating the motor patterns that underlie forward and backward walking.

High incidence of limb autotomy in a crab population from a coastal lagoon in the province of Buenos Aires, Argentina

A total of 2243 individuals of the shore crab Cyrtograpsus angulatus were obtained from Mar Chiquita lagoon, in the province of Buenos Aires, Argentina, from August 1986 to May 1987. Adult crabs were found at low tide on stones or on the beach, whereas juveniles were found beneath stones. Each crab was measured, sexed, and examined for the incidence of autotomized and regenerated limbs. Crabs exhibited a high, although size dependent, incidence of autotomy that was higher in female than in male adult crabs; the lowest values were found in juveniles. Crabs lost from one to seven limbs; both sexes showed a higher number of multiple, and a reduced number of single, autotomies than expected. The highest incidence occurred in the longest and most exposed limbs: the third and fourth walking legs; the chelae showed a reduced incidence. Crabs with multiple autotomy lost adjacent rather than nonadjacent limbs. The regeneration of a lost limb did not depend on the number of autotomies in small crabs, but it did in the case of large crabs which frequently did not regenerate some of their lost limbs. The five pairs of limbs had similar, size dependent, incidence of regeneration. Adult crabs with multiple autotomies had a lower proportion of synchronous regeneration of adjacent limbs. The high incidence of autotomy in this population of C. angulatus is discussed and alternative explanations of its causes are proposed, namely, inter- and intra-specific predation and agonistic behaviour.

Structure and Function of Cuticular Sensilla of the Lobster Homarus Americanus

ABSTRACT Chemosensory neurons and mechanosensory neurons innervate all the cephalothoracic appendages of the lobster Homarus americanus, including the antennules, antennae, six pairs of mouthparts, and five pairs of pereiopods. The structure and sensory function of sensilla on these appendages are described. Sensilla on the pereiopods and maxillipeds can be classified morphologically and physiologically. Smooth setae and squamous setae are the primary setal types in the rows and tufts of hairs on the walking legs; they also are found on the maxillipeds and, less abundantly, on the crusher and seizer claws. Serrate setae are common on the maxillipeds and the third and fourth walking legs. Hedgehog hairs are located on the cutting edges of the claws of the first two pairs of walking legs and on apposable cuticular surfaces on the last two segments of the fourth pair of walking legs. All four of these types of sensilla are both mechano- and chemosensitive. Sensilla sensitive to mechanical but not to chemical stimuli include peg sensilla, which are small sensilla situated in articulated sockets within cuticular depressions and are distributed over the surface of the carapace, pereiopods, and maxillipeds. Other mechanoreceptive sensilla include cuticular articulated peg organs (=CAP organs), located on the pereiopods and on the third maxillipeds, and campaniform sensilla, found on the antennae and antennules. Exclusively chemosensory sensilla were not found.

Oxygen transport in the blood of the tarantulaEurypelma californicum:pO2 and pH during rest, activity and recovery

pO2 and pH were continuously recorded by microelectrodes in hemolymph of the spiderEurypelma californicum before, during and after locomotor activity. ArterialpO2 values were obtained in the heart, and venouspO2 in the ventral sinus of the prosoma and in the coxa of the fourth walking leg. pH was recorded in the heart and in the ventral sinus.

日本海産ズワイガニの幼生期

In order to provide a detailed description of all the larval stages of Chionoecetes opilio, and determine a basis for future descriptions of all the species of the genus Chionoecetes, an ovigerous female crab was caught by the Danish seine fishery, on February 16, 1971. Hatching occurred on March 2 to 5. There are two zoeal stages and one megalopa in the larval development of Ch. opilio. The first zoea is 4.8 to 5.4 mm in length, 3.3 to 3.9 mm in width, and the second is 6.2 to 7.1 mm in length and 3.6 to 3.9 mm in width. The endo-podite of the first maxilliped has five segments with a spinal arrangement from proximal to distal of 3, 2, 1, 2, 5, and the second has three segments with a spinal arrangement 1, 1, 5. The megalopa is 2.9 to 3.3 mm in carapace length and 1.9 mm carapace width. Seven heavy processes are on the carapace: three rostral, a pair of anterior gastric lateral, and a pair of cardiac dorso-lateral. The fourth walking leg has no conspicuous hair projecting from the tip of the dactylopodite.

A Review of the Status of Orconectes inermis Cope and a Suggested Nomenclatorial Change

The blind crayfishes of the caves under the Cumberland Plateau have excited the curiosity of visitors and scientists since 1806. Written accounts are numerous and more than a century of conflicting literature has been produced. Hobbs brought this volume of material together when he revised the genus Cambarus in 1942. Tellkampf (1844) described the blind crayfish from Mammoth Cave, Kentucky, under the name, pellucidus. Erichson (1846) placed it in his new genus Cambarus where it remained until Creaser (1933) raised Fowler's subgenus Faxonius to generic rank restricting the genus Cambarus. Hobbs found this status existing when he began working on the crayfishes in the late thirties. With the description of Cambarus australis Rhoades (1941) from Alabama caves, it became evident that the hooks on the fourth walking legs represent a significant character for generic determination. In light of this new evidence, Hobbs (1942) redefined the genus. In naming the group, he pointed out that the genus Faxonius of Fowler (1912) was invalid by rule of priority. He further emphasized that one member of the genus had already been designated by the name Orconectes by Cope (1872). Thus, upon the erection and description of a separate genus, Cope's Orconectes must be applied. This generic change has met with popular approval and during the last fourteen years crayfish taxonomy has moved forward with new species described in most of the five new genera. Cope, though an eminent zoologist, was not a student of crustacea. When he visited the Indiana caves with Professor E. T. Cox, the state geologist, public announcements were expected from this wellknown scientist. The Indianapolis Journal of September 5, 1871 carried his off-the-cuff remarks regarding the mysterious denizens of the subterranean depths. The account specifically mentioned the blind crayfish, Astacus pellucidus given him by the state geologist. Cope's position as a carcinologist was hardly enhanced by his use of a generic name then nearly twenty-five years out of date! He did not even edit the error out of the account before it appeared in the Annals and Magazine of Natural History (1871: 368-370). In spite of his unfamiliarity with the field and apparently without consulting authorities on the group, he proceeded to name a new genus and a new species a few months later based upon a single second form male from Wyandotte Cave (Cope, 1872:419). The publication had no sooner appeared than Dr. Hermann Hagen, who had revised and monographed the crayfishes the year before, published a stinging satire (Hagen, 1872) on the hard-

STUDIES ON THE SECONDARY SEXUAL CHARACTERS OF CRAYFISHES. IV. MALES WITH TWO SETS OF SUPERNUMERARY MALE CHARACTERS

In study number three of this series, males of Cambarus propinquusand of Cambarus virilis which bore supernumerary male characters were described. These supernumerary char acters were in the form of copulatory hooks ordinarily found only upon the third walking legs but in these cases present also upon the second or the fourth walking legs. In C. virilis the extra hooks were confined to the second walking legs. In C. propi@@quus the additional hooks were found upon either the second or the fourth walking legs. It was predicted that in C. propinquus, since either the second or the fourth walking legs might function in carrying the extra hooks, specimens might be found in which copulatory hooks would be present upon both the second and the fourth walking legs. During the summer of 1924 large collections were made from practically all the streams and some of the lakes of southeastern