TRAVAUX iNtfDITS. 419 



probablement a un autre genre distinct voisin dcs Linnets 

 qu'il propose d'appeler Rigasia. 



Des trois genres que nous avons cites plus haul, il ne 

 reste done debout que le genre Mariwlla. Olui-ci a ete 

 etabli en 1855, par le docteur Gray (1) quilui donna pour 

 synonyme le genre inedit Clypeidella Valenc. MSS. (non 

 Clypidelfa, Swainson). Une seule espece fut decrite, la 

 M. Dussumieri. Je reproduis textuellement la description 

 du genre et celle de 1'espt'ce : 



Mantle or body convex, produced like a fleshy collar 

 in front, swollen behind, and separated from the upper 

 . part of the foot, in a cavity of which it lies; fringed on 

 '< the side. Foot compressed, truncated, and with an elon- 

 gate perpendicular gland behind. 



Shell quite hidden by the mantle, half ovate, solid, 

 with a thin, horny, more or less expanded edge. 



Clypeidella. Valenc. MSS. B. M. non Clypidella 

 Swainson. 



Marurlla Dussumieri. Foot produced behind, keeled. 

 truncated with a double edge. Mantle shield-like, free 

 in front, convex and separaL-J behind by a distinct 

 groove from the front past of the back of the foot : 

 a smooth above, with three slight keels on the hinder part, 

 a the central one the longest and most distinct. Back wi- 

 thout the least appearance of a hole. Back of the neck 

 with three grooves, central double, lateral diverging to 

 the hinder part of the side of the head. Shell com- 

 < pletely hidden, half ovate, elongate, solid, while, with a 

 a thin narrow corneous margin ; apex subterminal on 

 <( the right inner edge, internally horny, only slightly 

 u concave. 



Clypeidella Dussumieri, Valenc. MSS., french collec- 

 tion purchased in London. 



(1) Catalogue of Pulmonata in the rolleclion <>r the British Mu- 

 seum. l>art. I, p. C2. 



