HELIX-PARTHENA. 69 



Eurycratera, was proposed by Beck in 1837, without a line of defi- 

 nition. His list of species commences with H. falconeri Rve. The 

 remaining twelve species belong to nearly as many distinct groups. 

 Helicogena of Ferussac comprises most of the globose Helices, com- 

 mencing with H. aperta Born, a species of Pomatia. The type of 

 Swainson's Leiostoma is H. cornumilitaris, but the name is pre- 

 occupied. Finally, Parthena Albers has for its first species, H. 

 angulata Fer. ; so that, although he follows this species with a list 

 of four more belonging to four different groups, we may consider 

 angulata the type of the section. 



The species are mostly large ; they are confined to Hayti and 

 Porto Rico with the exception of H. jamaicensis. The subdivisions in- 

 dicated in the text are founded upon characters of but slight impor- 

 tance, but they are natural groups. 



** * 



Shell with light ground-color, variegated with darker spiral lines 

 and stripes, sometimes unicolored. 



H. ANGULATA Ferussac. PI. 6, fig. 55. 



Imperforate, depressed and almost flat above, very turgid beneath, 

 acutely carinated, fragile, covered by a very thin straw-colored 

 cuticle, obliquely striate, densely but very obsoletely granulate; 

 spire composed of 3 nearly flat whorls ; base extremely turgid about 

 the middle ; aperture subrhomboidal, large, scarcely oblique ; peri- 

 stome narrowly reflexed, upper and outer margins nearly straight, 

 angled at their junction at the periphery; basal margin arcuate. 



Alt. 20, diam. maj. 45, min. 32 mill. 



Porto Rico. 



H. angulata FER., Hist. t. 61, f. 1, 2. PFR., in Conchy I. Cab. t. 

 67, f. 1, 2. and Monogr. i, p. 297 ; REEVE, Conch. Icon. f. 230.- 

 H. inflata DESH., Encyc. Meth. ii, p. 258. Caracolla, inflata LAM. 

 An. s. Vert, vi, p. 97. (Eurycratera acutangula BECK, Index, etc., 

 p. 45, and Discodoma inflata SWAINS., Malacol., p. 329. teste PFR. 

 (Neither was described.) 



H. OBLITERATA Ferussac. PI. 6, figs. 51, 52. 



Imperforate, depressed, carinated, thin, light brown, narrowly 

 line ate or banded with umber, with oblique wrinkles of increment, 

 the entire surface densely granulate, the granules oval or elongated ; 

 spire convex, obtuse, apex minute ; whorls 4, rapidly widening, 



