Distribution Of Molluscs Research Articles

Some Fresh-water Larval Trematodes from Cheshire

The larval trematodes described in this paper were obtained from fresh-water molluscs collected from Rostherne Mere and a pond near Ashley, both in Cheshire. Rostherne Mere is a large sheet of water and carries an extensive fauna, vertebrate and invertebrate. The molluscs were collected from various fixed positions in the littoral region, and this method has confirmed previous observations (unpublished) in other stretches of fresh-water on the variation in the distribution and localisation of infected molluscs. How far this may be related to movements of the final host or to physical factors affecting the migration of the molluscs is at present uncertain; further observations are being made in an attempt to elucidate this problem. The molluscs were isolated in the laboratory in 3 × 1 glass specimen tubes, when the infected specimens were easily seen by the swarming of the cercariae, and all observations (including measurements) were made on these living, fully developed cercariae. Infected snails were later crushed in physiologically normal saline in order to obtain living sporocysts or rediae for examination. Measurements are, of necessity, only approximate owing to the slight pressure exerted by the weight of the cover-glass and the great powers of contraction and extension of these larval forms. Neutral red was used as an intra vitam stain; it also inhibits movement. Of the five species described four are new, the fifth, for which a further stage in the life history is described, being little known and not previously recorded for this country.

XXVI.—Reports of the Jasper Park Lakes Investigations, 1925–26. The Mollusca of Jasper Park

The following report deals with the systematics and distribution of molluscs collected in and around certain lakes in Jasper National Park, Alberta, Canada. For the sake of completeness some records published by Baker (2) are also included. The investigations of which this forms a part were made under the direction of Professor Charles H. O'Donoghue at the request of the Biological Board of Canada, and I desire to thank him for his encouragement and help throughout.

Societies and Academies

PARIS. Academy of Sciences, October n.—M. Henri Deslandres in the chair.—The president announced the death of Prof. Yves Delage.—G. Bigourdan: Corrections of the normal time-signals emitted by the Bureau international de 1'Heure from January 1 to March 19, 1920. Two tables give corrections of the ordinary partly automatic signals and of the beats 1 and 300 of the scientific signals.—Y. Delage: The application of the Pitot tube to the determination of the velocity of ships and to the registration of the distances traversed. The Pitot tube has been much used for the determination of fluid velocities with respect to immersed solid objects; it can also be utilised to determine the velocity of an object moving in still water, and its application to the measurement of the speed of a vessel is described in the present communication. Various devices are given for working the indicator at a distance from the Pitot tube, for rendering the indications independent of the variations of the load of the vessel, and for arranging that the movements of the needle shall be proportional to V and not to V2, so that from the continuous curve the total distance traversed can be estimated.—C. Moureti and G. Mignonac: The dehydrogenation of alcohols by catalvtic oxidation under reduced pressure. The general method described in a previous paper for the preparation of aldehydes and ketones by the catalytic oxidation of the corresponding alcohols by air in presence of reduced silver gives excellent results for the alcohols of low molecular weight, but the yield diminishes as the molecular weight of the alcohol increases. By working under reduced pressure {20 mm. to 40 mm.) this difficulty is removed.—P. Termier: The mylonites of the fourth Briangon écaille.—The secretary announced the death of M. Daniel Pauline Œhlert, correspondant for the section of mineralogy.—A. Chatelet: The enumeration and constitution of anv Abelian bodv whatever.—L. Antoine: The possibility of extending the homœomorphy of two figures to their vicinity.—J. Andrade: Friction and isochronism.—Ch. Déné: Waves of shock. The results of the study of a series of photographs of a stationary projectile placed in a stream of air moving at the rate of 45° metres per second. As the secondary waves are stationary, they can be more easilv photographed and studied.—W. A. Loth: A new method of navigation, permitting any vessel to enter and leave our (French) ports without risk when the usual means of determining the route are missing. An armoured cable traversed bv an alternating current with a musical frecmencv is laid on the sea-floor alonj the track to be followed, and a telephonic receiving apparatus of special design is carried bv the entering vessel. One oerson without specialised knowledge can brinf in a ship, as has been shown by oractiral trials at Brest.—R, Dubrisav: The application of a new method of physico-chemical volumetry. The solutions under examination are mixed with an equal volume of phenol and the temperature of miscibility is determined. The method has been applied to the study oi mixtures of solutions of sulphuric acid and sodium hydroxide, and two angular points are shown on the experimental curve corresponding to the formation of NaHSO4 and Na2SO4. It is noteworthy that when the neutralisation curve of sulphuric acid is followed by electrical conductivity or by cryoscopy no point corresponding to the formation of NaHSO4 is detected.—P, Bugnon: Causes of the transversal course of the libero-ligneous bundles at the nodes of the Gramineæ.—C. Beau: The trophic rôle of the endo phytes of orchids.—G. Astre: The biology of the molluscs in the French coast dunes and its relations with botanical geography. A discussion of the distribution of molluscs as affected by varying conditions of dryneÅ¡s. Apart from some secondary modifications of minor importance, the malacological fauna of the dunes is not one which has evolved in view of adaptation to a special medium, but a fauna already preadapted on the Mediterranean coasts, and which has simply extended its area of distribution.—P. Wintrebert: The aneural conduction of the ectoderm in the embryos of Amphibians.—M. Caullery and F. Mesnil: The existence of asexual multiplication in certain Sabellians (Potamilla Torelli and Myxicola dinardensis).—L. Besson: Relations between the meteorological elements and the number of deaths through inflammatory diseases of the respiratory organs in Paris. The data covered 522 weeks, and showed a clear relation between the number of deaths and the mean temperature three weeks before. From o° C. to 14° C. the fall in the number of deaths was proportional to the rise in temperature. Above 20° C. the deaths remained constant and independent of the temperature.

Chalk and the “Origin and Distribution of Deep-Sea Deposits”

Chalk and the “Origin and Distribution of Deep-Sea Deposits”

VII. Notes on the recent Ostracoda and Foraminifera of the Firth of Clyde, with some Remarks on the Distribution of Mollusca

A paper on recent Ostracoda and Foraminifera may seem rather out of place before a Geological Society, as communications of this kind usually find their way into other channels specially prepared for them. But when we consider the close relation of the present with the past, we perceive that much light may be thrown on the fossil fauna by a knowledge of the life-habits of existing forms; and no classes of animals are better fitted for this purpose than our minute Ostracoda and Foraminifera, extending as they do through all geological formations, and abounding in all seas and at all depths. Keeping in view the geological bearing of the facts, I propose to bring forward some particulars with regard to the variations in the groupings of species in different habitats and different localities, taking into account the depth of water and the character of the sea-bottom, together with the occurrence of species in one place compared with another, and their relative abundance or rarity. In drawing conclusions from the condition of the sea-bottom, we must remember that different groupings may be met with in mud, sand, or gravel of similar appearance, and often at no great distance from each other. Apparently slight differences in the constituents, chemical condition, &c., of the sea-bottom will account, in a great measure, for the absence or sparseness of a given species in one locality, and its abundance in another. However similar the habitat of a species may be at the bottom of the sea This 250-word extract was created in the absence of an abstract

XLII.—On the division of the European Seas into Provinces, with reference to the distribution of Mollusca

XLII.—<i>On the division of the European Seas into Provinces, with reference to the distribution of Mollusca</i>