Canal Pattern Research Articles

Ontogeny and phylogeny of the trunk lateral line system in cichlid fishes

An examination of the ontogeny of the lateral line trunk canal and the diversity of adult trunk canal patterns among cichlids indicates that bidirectional canal formation is a general ontogenetic pattern in the Cichlidae with the exception of Cichla and those few species with a complete trunk canal pattern. In addition to the tubed scales which make up the trunk canal, some lateral line scales have pits containing superficial neuromasts. These are recognized as components of the lateral line system of the trunk in adult cichlids for the first time. Eight trunk canal patterns that are variations on a simple disjunct pattern are defined among the 17 cichlid genera examined. Using bidirectional canal formation as a developmental model, these patterns can be placed along an ontogenetic spectrum. This suggests that heterochrony (alterations in the timing of development) is an important mechanism of evolutionary change in the lateral line system of the trunk in cichlid fishes.

The Character of Male Copulatory Organ and the Distributional Pattern of Normal Pore Canals in the Ostracode Genus Cythere

The male Copulatory organs, which are important for the Recent ostracode taxonomy, were compared in the ten Cythere species and the relationship between the copulatory organ and the geographic distribution was examined. For nine pairs of species whose geographic distributions overlap with each other, copulatory organs are morphologically different. Conversely, the pairs of species with similar copulatory organs show either of the following characteristics ; 1) their distribution-al areas completely isolated, or 2) their distribution-al areas are very close or more or less overlap each other, but their breeding seasons or their habitats are different. In the case of Cythere, consequently, the diversification of copulatory organ does not seem to reflect taxonomic distance between species. On the other hand, the number and the distribution of normal pore canals on the carapace were traced from the early stages when the distribution-al patterns are identical among all the Cythere species, to the adults which have their own patterns. As a result, the phylogenetic relationship of Cythere species was reconstructed with semi-quantitative estimation of the phylogenetic distance.

Gross Morphology and Evolution of the Mechanoreceptive Lateral-Line System in Teleost Fishes (Part 2 of 2)

The morphology and development of the mechanoreceptive lateral-line system in teleost fishes is reviewed, and the systematic distribution of defined types of lateral-line systems is summarized. The importance of an understanding of ontogeny is stressed and the roles of phylogenetic and developmental constraints in the evolution of the lateral-line system are discussed. Four types of head canal systems are identified on the basis of the relative development of the canals and the orientation of the neuromast receptors contained within them. The distribution of these patterns in the four major teleost clades is analyzed. It is suggested that a branched tubule system associated with the head canals is a primitive teleost character, while widened and reduced head canal patterns are convergent functional specializations in many taxa. The trunk canals are contained in a continuous series of lateral-line scales, and eight trunk canal patterns are described in teleosts. Given the correlation of the systematic distribution of the different trunk canal patterns, ecological habit and body shape, it appears that the trunk canals may function as a hydrodynamic monitor in swimming fishes.

Ancient Maya Wetland Agriculture: New Insights from Ecological and Remote Sensing Research

Abstract Despite claims that ancient Maya canals are found throughout the central Maya Lowlands, our study of satellite and aircraft imagery indicates that canals are concentrated in three regions: northern Belize, southern Quintana Roo, Mexico, and along the upper Candelaria River and its tributaries in Campeche, Mexico. Earlier reports of lattices of small canals in the karstic depressions, or bajos, of Peten, Guatemala, based on the analysis of airborne radar imagery, have not been verified with other remote sensing data or by field research. Our analyses of this same airborne imagery and Seasat satellite radar imagery demonstrate that the spatial resolution of, and speckle noise in, existing radar imagery make it inadequate for mapping lattice patterns of small canals. Radar imagery and Landsat Thematic Mapper imagery were, however, useful in mapping large canals, which in most cases are connected to lattices of smaller canals. Furthermore, our analyses of wetland soils, vegetation, and hydrology conf...

Lateral line system during the life cycle ofanguilla anguilla(L.)

Abstract The maturation of the lateral line system in Anguilla anguilla (L.) is described. The various stages of eel (glass‐eel, yellow eel, silver eel), which are characterized by different degrees of swimming activity were compared, and changes were observed in the lateral line system during the transition from yellow eel to silver eel. The most evident changes occur in the pattern of the head canals and in the continuation of the lateral body canals as far as the caudal fin. These changes appear to be related to the greater swimming activity displayed by the silver eel.

Pattern of vascular canals in the bone extremities of the pelvic appendicular skeleton in broiler type fowl

Broiler fowls were reared from hatching till 20 weeks old. Birds were killed throughout the growth period and the bone extremities of the pelvic appendicular skeleton prepared for study. The patterns of vascular canals in these broiler fowls were very similar to earlier reports in laying strain fowls. There was a great range of and variation in the vascular morphology of broiler fowl. The physeal vasculature of the rapidly growing broilers was frequently disrupted, and such areas were often associated with dyschondroplastic lesions. The rapidly growing bone extremities in broiler fowls were susceptible to occlusion of epiphyseal vascular canals. Lesions were frequently seen at similar sites in different specimens. Links are suggested between the growth rate, weight and behavioural characteristics of broiler fowls and the development of lesions.

A pachyosteomorph arthrodire from Gogo, Western Australia

A new monotypic genus of eubrachythoracid arthrodire is described from die Upper Devonian Gogo Formation of Western Australia as Incisoscutum ritchiei gen. et sp. nov. It is at die pachyosteomorph level of organization, having no contact between the plates of die flank and those of the ventral shield behind the pectoral fin. It is interchangeable widi Coccosteus spp. and a number of earlier described Gogo forms in a sketch dadogram for arthrodires, but its phylogenedc relationships are unknown. Well preserved material of die scapulocoracoid throws new light on die structure of this element in arthrodires, particularly widi respect to variations in die pattern of canals and foramina.

Functional morphology and evolution of the cystoidEchinosphaerites

Echinosphaerites, known from the Lower and Middle Ordovician, has branched biserial brachioles. Such features are so far unknown in the Rhombifera. Echinosphaerites had a skeletal meshwork like that of other blastozoan echinoderms, with a fine outer mesh layer and an inner coarse mesh layer. During evolution the number and location of brachioles, including the pattern of brachiole branching, changed by increase in the number of brachioles and increased complexity of the branching pattern. The exothecal pore structures increased in the complexity of patterns of tangential canals. The pattern of skeletal growth in Echinosphaerites is discussed. The Echinosphaeritidae and Caryocystitidae families are closely related and show parallel development.

The course of resin canals in the shoots of conifers

Resin canal patterns in the Pinaceae differ significantly from those in other conifers. In this paper, Pinus type, Picea type and Larix type are defined.Pinus has the Pinus type pattern, in spite of the possession of a system of peripheral canals in some members. The patterns inAbies, Picea, Cedrus, Keteleeria andPseudotsuga are varied. Both Pinus and Picea types are usually observed, although many other types are also seen in these five genera.Larix andPseudolarix have the Larix type pattern, andTsuga has a modified Torreya type pattern.From the data obtained in the present series of studies (Suzuki, 1979a, b), two main evolutional trends of resin canal patterns are suggested. In the Pinaceae, the patterns probably evolved from the complicated type to the simple type. In the other families, they evolved from the simple type to the complicated type. Moreover, it is to be considered likely that the patterns have evolved independently in each family.Patterns of resin canals are very similar to the primary vascular patterns. The similarity is probably not fundamental, but superficial, because most of the conifer species, of which resin canal patterns are varied, have but a single type of the primary vascular system.

The course of resin canals in the shoots of conifers

The course of resin canals in stem cortex and the continuity between resin canals in leaves and those in stem cortex were investigated. The present paper is the first of three parts of the investigation. In this paper, fundamental features of resin canals and actual resin canal patterns in the Taxaceae, Cephalotaxaceae and Podocarpaceae are reported. From the observation of serial transections of shoots, composite diagrams and three-dimensional models of resin canal patterns are drawn. Central canals, if present, run vertically in stem cortex and sometimes divide, end blindly or unite each other. The distance between two adjacent central canals fluctuates rhythmically in connection with the vascular supply from the stem to leaves. The resin canal patterns of the families are classified into four types. Those ofTaxus, Nothotaxus and three species ofDacrydium belong to the Taxus type, those ofTorreya andCephalotaxus to the Torreya type, those ofDacrydium elatum, Podocarpus alpinus, P. elatus, P. elongatus andP. neriifolius to the Dacrydium type, those ofP. macrophyllus, P. nagi andP. koordersii to the Podocarpus type.

Valve orientation and functional morphology of the foramen of some siphonotretacean and acrotretacean brachiopods

It has recently been suggested that the foramen of siphonotretacean and acrotretacean brachiopods functioned as an exhalant siphon and that it was a feature of the dorsal valve. In representatives of these superfamilies the pedicle was considered to have emerged from between the valves. Re-examination of the evidence on which these arguments were based suggests that some of it is capable of more than one interpretation. The remainder, together with consideration of the mantle canal patterns, cemented mode of attachment, and comparative morphology of some discinaceans and siphonotretaceans, strongly supports the traditional view that the foramen of these forms was located in the ventral valve and that it served as a pedicle opening.

Cercaria chackai sp. n. (Transversotrematidae) from Kerala, India

The new cercaria develops in simple rediae in the freshwater snails, Melania tuberculata and M. scabra. It differs from known transversotrematid cercariae in size and in features of the excretory system, including the pattern of canals, extent of cilia in them, topography of excretory com- missures, and number and arrangement of flame cells. A survey of the cercarial fauna of Kerala revealed a new transversotrematid larva de- veloping in the freshwater snails, Melania tuberculata Muller and M. scabra Muller, from Chackai, near Trivandrum City. Of 525 snails, 39 were infected with the new species which is named Cercaria chackai sp. n. and described below. At present, the family Transverso- trematidae included only the type genus and certain cercariae have been allocated to that genus to which the new species may prove to belong. Soparkar (1924) described the first trans-

An examination of the cuticle of three species of Ricinulei (Arachnida)

A study of the cuticle of Ricinoides sjostedti, Ricinoides afzelii and Cryptocellus lampeli has been carried out using staining and histochemical tests in an attempt to determine its chemical composition and to relate it to other arthropod cuticles. The examination has revealed that the cuticle of ricinulids differs in several ways from other arthropods studied and shows most similarity to the spider and king crab cuticle. Histochemical tests failed to reveal the presence of sulphur, an element occurring in the cuticle of other arachnids. Insufficient material prevented the use of strong oxidizing methods to determine whether or not sulphur does occur in the cuticle. A description is given of the pore canals in the ricinulid cuticle. The structure and pattern of the pore canals is different from that seen in any other arthropod so far described.

The anatomy of the atrioventricular conduction system in ventricular septal defect and tetralogy of fallot: correlations with the electrocardiogram and vectorcardiogram.

The atrioventricular conduction system was studied by a technique of selected serial histological sections in examples of tetralogy of Fallot and ventricular septal defect to correlate the anatomic findings observed with the electrophysiological findings as manifested by the vectorcardiographic pattern. Eight hearts were studied; two examples of each anomaly had electrocardiographic and VCG patterns in the frontal plane similar to A-V canal defects and two examples of each had ECG and VCG patterns usually associated with these lesions. Of the four examples of tetralogy, the two examples with VCG patterns similar to the A-V canal pattern differed from the other examples in that the distance between the A-V node and the origin of left bundle branching was shorter and the fibers destined to become the right bundle branch took an elongated course. The VSD examples offered less striking differences. A short distance from the A-V node to the onset of left bundle branching was seen in both examples with VCG patterns similar to the A-V canal pattern, but one example of VSD with a representative VCG pattern had a similar anatomic configuration. When measurement ratios were compared, the right bundle took its origin at a relatively greater distance from the A-V node in the examples with VCG patterns similar to the A-V canal pattern. The anatomic configuration of those examples of tetralogy and VSD with VCG patterns similar to the A-V canal pattern was such that relatively early conduction to the left bundle branch system could occur.

The Pattern and Structure of Excretory Canals in Avitellina centripunctata Rivolta 1874, an Anoplocephaline Cestode from Sheep and Goats, with a Note on the Functions of Excretory Canals in Cestodes

The Pattern and Structure of Excretory Canals in Avitellina centripunctata Rivolta 1874, an Anoplocephaline Cestode from Sheep and Goats, with a Note on the Functions of Excretory Canals in Cestodes

OBSERVATIONS OF MARS MADE AT MOUNT WILSON IN 1954

Observations of Mars were made at Mount Wilson in the spring and summer of 1954 with a motion-picture camera at the Cassegrain focus of the 60-inch telescope and at the coude focus of the 100-inch. This program, which had for its main objective the photography of the canals, has already been discussed.1'2'3 It was hoped that photographs could be obtained during moments of super-seeing when the whole canal pattern flashes out for a few seconds. On none of our nights, however, was the seeing rated better than 4 on a scale of about 10. Nevertheless, on our best images we have found seven markings which can be identified with known canals. The fact that we were able to record a few