HELIX. 73 



superne subangulatus, subito deflexus, basi inflatus, antice gibbus et valde 

 constrictus ; apertura perobliqua, ringens ; perist. acutum, late reflexum, 

 marginibus vix conniventibus, laminas elevatas in ventre anfractus penul- 

 timi angulatim junctas, emittentibus, dextro lamina subperpendiculari, 

 dilitata, basali dentibus 2 acutis munito. 



SYNONYMS AND REFERENCES. 



Helix ventrosula PFEIFFER, Proc. Zool. Soc. 1845, p. 131; Mon. Hel. Viv. i. 417; 



iii. 266. 



CHEMNITZ, ed. 2, i. p. 373, (1846,) pi. Ixv. figs. 5, 6, (1849). 

 REEVE, Con. Icon. No. 687, (1852). 



DESCRIPTION. 



Animal not observed. 



Shell minutely perforated, globosely depressed, thin and 

 shining, pellucid, delicately striated, horn-colored ; spire 

 slightly raised, whorls 5 but little convex, the last one 

 subangulated at the periphery, falling suddenly towards 

 the aperture, inflated below, and strongly contracted ; 

 aperture very oblique, much complicated with teeth ; 

 peristome acute, broadly reflected, its terminations scarcely 

 approaching each other, but joined by two white, elevated 

 laminae, which are placed at acute angles on the parietal 

 wall ; the basal termination is also furnished with two 

 white acute denticles, while on the other is placed a white 

 sub-perpendicular, extended lamina. 



Greater diameter, 13 ; lesser, 11 ; height, 1\ millimetres. 



Geographical Distribution. Texas and Mexico. 



Remarks. This shell was unknown to Binney, and 

 erroneously considered by Gould (p. 193) as a synonym 

 of H. Texasiana. It is, however, a remarkably well char- 

 acterized species. It may readily be distinguished by the 

 globose under-surface, and the basin-shaped aperture, nar- 

 rowed to scarcely more than a chink by the prominent, 

 white teeth. 



HELIX AURICULATA SAY ................... vol. ii. p. 186, pi. xl. fig. l. 



Polyyyra auriculata SAY, (Binney's ed.) p, 10. 



10 



