VITRINlD-a;. 21 



YiTRiNOZONiTES, Biiiney. 



l)is{r. — V. latUsima^ Lewis. Tennessee. 



Shell like Vitrina. Animal having a caudal mucous pore with 

 longitudinal furrow ; no appendiculate mantle-process ; marginal 

 teeth of radula simple, not bifid. 



Yelifera, Binne3\ 



Bistr. — F. Gabbi, Binne3\ Costa Rica. 



Shell as in Helicarion. Animal : mantle with one or more 

 accessory processes which cover most of the shell ; a simple 

 longitudinal mucous pore, without horn-shaped process ; jaw 

 with smooth anterior surface, and beak-like projection on the 

 cutting edge ; radula resembling Zonites. 



Parmella, H. Adams, 186T. 

 Bistr. — P. planata, H. Ad. (xcii, 19). Fiji Isles. 

 Animal undescribed. Sliell depressed, spire flat, epidermis 

 horny, polished, extending greatly beyond the posterior part of 

 the margin. 



Yitrinoidea, Semper, 18t3. 



Bistr. — V. Albaiensis^ Semper. Philippines. 



Shell wholly concealed by the mantle, with cuticle and cal- 

 careous layer, forming several whorls ; respirator}^ orifice before 

 the middle of the mantle ; no caudal mucous pore ; marginal 

 teeth of the radula three-pointed ; jaw smooth ; accessor}^ glands 

 at the genital organs ; no flagellum. 



YiTRiNOPSis, Semper, 1870, 

 Bistr. — 2 sp. Philippines. V. tuberculata, Semper. 

 Two lobes of the mantle covering a part of the shell in front 

 and on the left side, not on the right as in Yitrina. Lateral 

 teeth of the radula three-pointed, not 1-2 pointed as in Yitrina. 



YiTRiNOCONUS, Semper, 18T3. 



Bistr. — 9 sp. Philippines. V. cyathus^ Pfeiffer. 



Shell ambilicated, conical or trochiform, apex obtuse ; whoi'ls 

 planulate, the periphery carinate or angulate ; aperture lunate ; 

 peristome simple, acute or thickened. 



Mantle sometimes with cervical lobes, but no shell-lobe ; 

 lateral teeth of the radula two-pointed. 



Laconia, Gra}'-, 1855. 



Bistr. — 1 sp. L. Ferussaci, Gray. 



Body subgiobose ; mantle edged, produced in front, forming a 

 broad collar. 



Shell subgiobose, entirel}^ and permanently covered bj- a thin 

 expansion of the mantle ; spire of few whorls, the last very large ; 

 aperture very large, lunate. 



