300 ROTELLID^. 



lar ; peritreme continuous, inner lip thickened and arcuate, outer 

 lip with the margin thickened ; umbilicus crenulate. Japan. 

 G. crenellifera^ A. Ad. (Ixxix, 92). 



MORCHiA, A. Ad. Shell obliquely ovate, depressed, widely 

 umbilicated, convex above, flat beneath ; whorls rapidly 

 increasing, the last dilated, ascending and embracing the other 

 whorls as far as the apex ; aperture oblong, oblique, somewhat 

 horizontal, dilated below, narrowed above; peritreme continuous, 

 thickened. Japan. G. obvoluta^ A. Ad. (Ixxix, 93). 



ciRSONELLA, Augas. Shell minute, globosely turbinate, smooth, 

 narrowly umbilicated ; aperture circular, peritreme continuous, 

 slightly thickened. G. australis, Angas (Ixxix, 94). 



Discopsis, Folin. Shell discoidal, depressed, umbilicated ; 

 margins of the oblique aperture canaliculately joined upon the 

 penultimate whorl. 2 sp. W. Africa. 



Family ROTELLID^. 



Shell more or less lenticular, polished ; umbilical region covered 

 by a large, convex, subvitreous callus. Operculum thin, cor- 

 neous, ciliated on the outer edge ; animal with rudimentary 

 rostrum ; frontal lobes greatly developed. 



RoTELLA, Lam. 



Etym. — Diminutive of rota^ a wheel. 



Syn. — Globulus, Schum. IJmbonium, Link. 



Distr. — 20 sp. India, China, Japan, Philippines, N. Zealand. 

 B. Zelandica (Ixxix, 95, 96). Fossil. Devonian — . 



Shell depressed, lenticular, the spire depressed conical ; aper- 

 ture semiorbicular, outer lip sharp ; base with a convex, rounded 

 umbilical callus. 



Animal. The lateral fringe of the foot is distinct, with three 

 tentacular filaments on each side ; at the front of the right side, 

 near the base of the tentacles, it is produced into an oblong, 

 fleshy lobe. The right tentacle is the larger and free, with an 

 oblong, compressed lobe on its hinder side which has an indis- 

 tinct indication of an eye ; the left tentacle is smaller and partly 

 attached to the upper side of the left eye-pedicel, which is cjdin- 

 drical, bearing a very distinct eye, and furnished with a large, 

 membranous expansion attached to the whole of its length on 

 its left side, and which is fringed at the edge. This frontal 

 appendage, when the animal is alive, is folded on itself to form 

 a tube, which has caused it to be mistaken for a siphon. 



ETHALIA, H. and A. Adams. (Fseudorotella,' Fischer.) Whorls 

 convex, smooth or transversely^ striated ; cokimellar lip termi- 

 nating anteriorly in a callosity. Scarcelj^ diiiering from the^ 

 typical group. R. Guamense, Quoy (Ixxix, 9t). 



HAPLOOOCHLIAS, Carpenter. Shell like Collonia, but not pearly • 



