MELANOPSIS, 



ly Audehard. 



Melanopsis et Pirena, Lam. 



TESTA oblonga, fusiformis, vel conico-cylindra- 

 cea, apice, (nisi erosione perierit) acuto; spird 

 anfractibus 5 ad 15, ultimo plerumque maximo ; 

 apertura oblonga vel ovali, superne acuta, infra 

 emarginata; columelld contorta, callosa, su- 

 perne incrassata, subtus subtruncata, lahio ex- 

 terna interdum profundi emarginato. Opercu- 

 lum corneum, parvum, spirale. 



^^Thb Genus Melanopsis/' established by M. le Baron 

 d'Audebard de Ferussae, in 1807, " is one of the most 

 interesting of molluscous animals^ on account of the 

 importance of facts proved by its fossil species, in con- 

 nection with the history of the tertiary formations. It is 

 not less worthy of attention in a zoological point of view, 

 because it shows a sort of transition from the operculated 

 to the semi-operculated Pectinibranchia, that is, from 

 those Pectinibranchia whose shells have an entire aper- 

 ture without a canal at its base, and whose operculum 

 entirely covers the aperture, to those the base of whose 

 aperture forms a more or less distinct canal, destined to 

 receive a fold of the mantle, which conducts the water to 

 the branchial cavity, and whose operculum is neither so 

 large nor of the same form as the aperture."* 



We are not aware that any of the Melanopsides are 

 marine, for all the recent species occur either in rivers or 

 lakes, and yet most of the fossil species are found in beds 



* De Ferussae in the Memoires dc la Soci^^t^ d'histoire naturclle de Pjris," 

 p. 133. 



