CURRENT LITERATURE. 93 



depressed ; the spire almost flat ; the whorls much wider ; the surface, although 

 it appears to be quite smooth, is similar to Ply. radiatula, Gray, though the lines 

 are much finer. 



Veronicella dissimilis, (Journ. Inst., Jamaica, p. 134, 1822.) 



Mr. T. D. A. Cockerell describes this slug from Moneague, Jamaica. 

 Anatomically it closely resembles V. sloanii, Simroth. 



New Species of Spondylus and Helix. (Jy. Conch., p. 70, 1892.) 



Mr. Edgar A. Smith describes S. poivelli from Madeira, and//. {Grotochits) 

 hcdlcyi, the latter described from a single shell, its nearest allies are mentioned, 

 and the chief difference wherein it differs from H. exsultans 



Additions to the Shell-fauna of the Victoria-Nyanza. (Ann. and Mag. 

 N.H., p. 380, 1892.) 



Mr. Edgar A. Smith enumerates the five species lately recorded by 

 Dr. E. von Martens, and describes the following new species collected by the 

 Rev. E. Cyril Gordon, and recently presented to the British Museum. Ampullaria 

 nyanscc, A. gordonii, Planorbis victoria:, and Sphcerium nyanzce. These are the 

 first records for Ampallaria and Sphcerium from the Lake, the latter being only 

 sparingly met with in Africa are of interest. 



On the Land Shells of St. Helena. (P.Z.S., p. 258, pi. xxi.-xxii, 1892.) 

 Edgar A. Smith. 



New Species of Diplommatina from Assam. (P.Z.S., p. 507, 1892.) 

 Lt.-Col. Godwin-Austen. 



SHELL. 



On the Mode of Growth and the Structure of the Shell. (P.Z.S., 



p. 528, 2 pi., 1892. ) 



Mr. B. B. Woodward has been investigating the mode of growth and the 

 structure of the shell in Velates conoidcus, Lam., and other Neritida. " The 

 Neritidcs avail themselves largely of the molluscan faculty of removing portions 

 of the shell that may be in the way of the animal in the course of its growth, 

 and some of them in this manner convert the interior of their tenement into 

 a single open chamber, across which there projects from the sides, immediately 

 behind the posterior portion of the columellar lip, a septum that takes the place 

 of the columellar and serves as a point of attachment for the posterior retractor 

 muscle." A series of stages are described showing the " removal of the columella 

 and inner walls of the whorls and the development of the septum. In V. conoidcus 

 " during the early stages of its growth the myophore is formed of the remnant of 

 the parietal wall strengthened by shelly deposit. No trace of a prominence is 

 perceptible at first, but by the time 3i whorls are finished it is plainly discernible, 

 and with the completion of the 4th whorl it attains its maximum development." 

 The growth of the septum is now fairly rapid, it becomes thickened and pillar- 

 like, and still later (4^ whorls) the septum only constitutes the myophore, having 

 absorbed the columella and paires. The callus then becomes greatly thickened, 

 and additional matter is added to the outer lip columellar and around the plane 

 of the outer lip. Many other stages are described and figured, also the 

 periostracum, the chemical composition and microscopical structure of the shell. 

 Want of space prevents us from doing justice to this most interesting and valuable 

 paper. So little has been written on the shell (worth reading) in this country, 

 that Mr. Woodward has placed conchologists under a debt of gratitude for so 

 careful and painstaking an investigation. A similar study on Ampullaria would 

 be interesting. W. E. C. 



