Cyclostrema, Adeorhis, Vttrinella, and related genera. 119 



by a thin, very lustrous glaze or layer of enamel, not in any sense a 

 thickened pad, as in Teinostotna. 



Shell thick, solid, porcellanous, slightly tinted with yellow along 

 the suture and on the base ; flattened above and below, with the in- 

 dented umbilical region covered with a thin 

 lustrous glaze or layer of enamel. Surface 

 smooth and very lustrous, marked only by irregu- 

 lar, microscopic, growth lines. Suture incon- 

 spicuous. Whorls about 2^, coiled in the same 

 plane, lapping well on 'to each other, rapidly 

 enlarging, with a very small nuclear whorl and 

 large body-whorl, Aj^erture very oblique, some- 

 what ovate ; peritreme not continuous, modified 

 into a thin, inconspicuous glaze on the body- 

 whorl, elsewhere with rounded edge, with a slight callous deposit 

 beneath the suture where the outer-lip extends obliquely well for- 

 ward from the body-whorl, with little, if any, curvature and forms a 

 slight sutural notch. 



Greatest diameter, about rs""™; height, about -S"'™. 



In form, this species approaches Teinostonia cryptospira (Verrill) 

 Dall, but it is a much smaller shell, with the whorls quite differently 

 coiled and with the umbilical callus represented by a thin glaze. 



Calceolina A. Adams, 1863. Type, C. imsilla C. B. Adams. Jamaica. 



"Shell like a Neritina, oblong, depressed, with small spire. 

 Whorls rapidly increasing ; umbilical region callus. Aperture 

 semi-circular, interior not pearly with the inner lip concealed by a 

 large, broad callus covering the umbilicus behind, with a simple, 

 straight, fi-ont edge." 



Type, C. pusilla C. B. Adams. Ann. Mag. N. H., xi, p. 267, 1863. 



The type was described by C. B. Adams as a Neritina, which it 

 very strongly resembles, so that I question its rightful relation to 

 this group of shells, but H. and A. Adams, Fischer, and Tryon, all 

 used the genus as a section under Teinostoma.^ 



1 The genus Discopsis de Folin, 1869, (type, D. omalos de Folin, "West Indies) 

 (Fonde de la Mer, i, pp. 190, 205, pi. 23, f. 6, 1869) is also placed by Fischer, Tryon, 

 and others as a sub-genus under Teinostoma. Judging from the description and 

 figures as given by Tryon, it seems to me very distinct. The genus Cochliolepis 

 Stimpson, 1859 (type, C. parasiticus St., Charleston, S. C.) (Proc. Boston Soc. Nat. 

 Hist., vi, p. 308, with three cuts, 1857-1859) was placed by Mr. Dall next Discopsis 

 (Bull. U. S. Nat. Miis., No. 37, p. 162, 1889), but he also suggested its possible rela- 

 tion to the genus Vitrinella (Bull. Mus. Comp. Zool., xviii, p. 360, 1889). 



