on M, Deshayes's Monograph of Dentcdium. 197 



show that I have not confounded them, but considered them as distinct. 



" The London clay and tlie calcaire grosser swarm with several 

 " sorts not easily distinguishable from the recent species, among which 

 " we may particularly remark the fossil species from Piacenza which 

 " so nearly resembles D. elephantinum that Brocchi 1ms not hesitated to 

 " refer it to that species,'' Sowerby, Genera No. XV. and in the 

 description of the plate. 



" Fig. 2. D. elephantinum, fossil, according to Lam. and Brocchi.'' 



4. D. aprinum. 



It does not appear to me certain that Deshayes's D. aprinum is the 

 same as Linne's, however, as the only difference consists in the colour, 

 and as Deshayes's D. aprinum might lose its colour and become w^hite by 

 long exposure, no confusion will be created by the adoption of his species 

 as the true aprinum. 



5. D. octogonum. 



As far as I am able to judge from a very extended collection of 

 Dentalia, the proportions must be considered as important in drawing up 

 their distinguishing characters : should this prove to be the case, another 

 octogonal species, whose proportions differ very materially from those of 

 D. octogonum, will be added to the Ikt. 



7. D. variabile. 



The late Mr. G. Humphrey possessed many individuals of this beauti- 

 ful little species, which he distinguished as the " Chain-ridged Dentalia 

 *' from the East Indies." 



18. D.entalis. 



From the careful examination of many specimens, I am convinced that 

 Lamarck's var. B. of his D. Tarentinum should be considered as distinct 

 from D. entalis, and might, without impropriety, be called D. Tarenti- 

 num ; there is also a variety of D. entalis with a reddish apex. 



19. D. politum. 



Linne's descriptions of Z). politum and D. eburneum accord so pre- 

 cisely with my D. circinatum and D. eburneum, (Genera of Shells, No. 



