ROTELLID^. 301 



aperture circular, varicose ; columella not callous. Animal and 

 operculum unknown. Its affinities may be with Ethalia. R. 

 cyclopJioreus, Carp. Cape St. Lucas. 



PAEKERiA, Gabb. ( After C. F. Parker, curator of the Philada. 

 Academy.) Shell minute, in form like Rotella, but with the 

 shell-substance vitreous and transparent or translucent like 

 Yitrinella; inner lip thickened, and the umbilicus covered with 

 a not very heavy c;illus as in Rotella. Miocene ; W. Indies. 1 

 recent species. B. vitrea, Gabb (Ixxix, 98). 



TuRBTNA, de Koninck, 1881. 



Distr. — 4 sp. Carboniferous; Europe. T. deornatus, 'Kon. 



Shell top-shaped, thin and fragile, smooth ; spire of 5-8 convex 

 whorls; mouth large, transversely^ rounded, the margin sharp, 

 not thickened, columella not twisted ; umbilicus narrow and 

 deep, sometimes wanting. 



Plocostylus, Gemmellaro, 1878. 



Distr. — Liassic, Jurassic ; Italy. P. tyjjus, Gemm. 



Shell top-shaped, thick, smooth ; spire obtuse ; whorls rapidly 

 enlarging, the last very large, rounded ; base more or less flat- 

 tened ; mouth round ; inner lip straight, short, ending in an 

 anterior fold, forming a tubercle ; outer lip obtuse. 



Teinostoma, H. and A. Adams. 



Distr. — 8 sp. Philippines, Japan, Mazatlan. T. politum, A. 

 Ad. (Ixxix, 99). 



Shell orbicular, depressed, subspiral, polished or spirally 

 striated, last whorl rounded, or angulated at the periphery ; 

 umbilical region covered with a large, flat callosity ; aperture 

 transverse ; inner lip smooth, callous ; outer lip thin, simple, 

 not margined or reflected. 



calceolina, a. Ad. Shell neritiform, oblong, depressed ; spire 

 small ; whorls rapidly increasing, umbilical region callous ; 

 aperture semicircular ; inner lip with a large wide callus, covering 

 posteriorly the umbilicus ; margin of the callus straight, simple. 

 Japan. T. pusilla, Ads. (Ixxix, 100). 



[Cyclora, Hall. 



Distr. — G. minuta, Hall. Palaeozoic; Ohio. 



Subgiobose, thin, small, spire short, consisting of a few whorls ; 

 columella smooth, slightly reflected over a minute umbilicus ; 

 aperture circular. See p. 223.] 



Anomphalus, Meek and Worthen. 

 Distr. — A. rotulus^ Meek and Worthen (Ixxix, 1). Carbon- 

 iferous ; Ills. 



Shell depressed, sublenticular, imperforate, smooth, volutions 



