CURRENT LITERATURE, 1 49 



Part 55 contains the Polyplacophora. Thirteen new species are described ; 

 five only are figured, which is disappointing in a "fully illustrated" monograph. 

 An excellent artificial key to Chiton (sc/isu stricto) is provided ; the species, 

 however, are grouped geographically, which is the most convenient method. 

 Part 31 continues the supplement to the Helicidcc up to Helix [candiduld). The 

 following, though not so marked, seem new: Tracliycystis, a section of P/iasis, 

 Albers; and Trochomorpha neglecta (allied to T. kartmanni, Pfr.). — E. R. S. 



STRUCTURE AND DEVELOPMENT. 



Anon. — The Hermaphroditism and Viviparity of the Oysters of the N.W. Coast 

 of the U.S. Ann. and Mag. N. H., 1893. 



Bergh, R. — Opisthobranches provenant des campagnes du yacht ITIirondelle. 



Rcsultats des Camp. Sci. accomplis sur son yacht par Albert Ier, Prince 



Souverain de Monaco, Fasc. iv. , pp. 1-40, Plates i-iv., Monaco, 1893. 



Anatomical descriptions of various Atlantic Opisthobranchs, including a new 



genus, Pleurobranchillus. The author corrects a few mistakes made in his memoir 



on the Marseniada. For list of species described see page 149. 



Biihmig, L. — Zurfeineren Anatomie von Rhodope veranii, Kolliker. Zeit. f. wiss. 

 Zool., 1893, l y i-> i-> pp- 40-116, pis. iii-vi. 

 Bohmig gives the results of an elaborate investigation into the minute anatomy 

 of this aberrant little creature. Ranked as a Gastropod by Kolliker, Rhodope was 

 excluded from the Mollusca by Trinchese and Bergh, and consigned by them to 

 the Turbellaria, from which group Lang referred it back again to the Mollusca. 

 Bohmig here satisfactorily shows that the central nervous system, the alimentary, 

 excretory, and reproductive systems of Rhodope conform to types which are 

 certainly not Turbellarian, and which closely approach those exhibited in the 

 Nudibranchiate Gastropoda. The impression that Profs. Lankester and Lang 

 were perfectly correct in regarding Rhodope as a highly degenerate Nudibranch is 

 emphatically strengthened by a perusal of the present memoir. The only serious 

 difficulty attending this view is the absence of a veliger-stage from the life-history 

 of Rhodope, — an extreme abbreviation of development which is, nevertheless, not 

 without its parallel in other groups. — W.G. 



Bouvier, E. L. — Observations nouvelles sur les affinities des divers groupes de 

 Gasteropodes. Comptes Rendus, 1893, cxvi. , pp. 68-70. 



Hitherto, the Prosobranchia have been sharply separated from the Opistho- 

 branchia and Pulmonata on account of the chiastoneurous nature of the nervous 

 system. 



M. Bouvier, in his interesting paper, states that he has for some time felt 

 convinced that they formerly were united by some transitional form. In Actieon 

 solidulus he not only finds a transitional form between the Prosobranchia and 

 Opisthobranchia, but also one which closely connects this latter group with the 

 Pulmonata. In Actieon the nervous system is decidedly chiastoneurous, as in the 

 Prosobranchia. The author discusses the various problems that arise in tracing 

 the descent of the Opisthobranchia and Pulmonata from the Prosobranchia. 



We trust that a further detailed account of so interesting a piece of work will be 

 forthcoming. The absence of illustrations detracts from the value of the paper. — 



W.E.C. 



Fischer, P., and Bouvier, E. L. — Sur l'enroulement des Mollusques univalves. 

 Journ. de Conchyl., 1S92, pp. 234-45. 

 A reply to Dr. Pelseneer's paper. Mention is made of the fact that, as pointed 

 out by Dall, several species of abyssal Calliostoma have the larval shell sinistral. 



Fischer, H. — Note sur l'enroulement de la coquille des embryons des Gastro- 

 podes. Journ. de Conchyl., 1892, pp. 309-13. 



