68 HELIX-PARTHENA. 



rather separated, rough, irregular, frequently anastomosing, at the 

 periphery always bifurcating, so that there are about double as many 

 striae on the base as there are costulse above ; the sculpture becoming 

 obsolete in the center of the base, which is glossy. Whorls 3J to 4, 

 rapidly increasing, the last oblong, transversely dilated, abruptly 

 descending and gibbous behind the aperture ; aperture extremely 

 oblique, small, truncate-oval ; peristome expanded, heavy, thickened 

 inside and on its face, upper and outer margins arcuate, basal mar- 

 gin horizontal, straight, bearing a slightly prominent obtuse tooth 

 near the insertion of the columella. 



Alt. 17, diam. maj. 29, min. 22 mill.; alt 20, diam. maj. 34, min. 

 27 mill. 



Jurisdictions of Baracoa, Guantanamo and Holguin, E. Cuba. 



H. baracoensis GUT. in POEY, Memorias, ii. p. 26 (1856-58.) 

 PFR. Monogr., iv, p. 217. ARANGO, Fauna Mai. Cub., p. 71. H. 

 lamellicosta (GuNDL.) PFR., Malak. BL, vii, 1861, p. 220, and Novit. 

 Conch, p. 185, t. 50, f. 4-6. ARANGO, Fauna, etc., p. 71. 



Diagnostic characters of this form are the depressed shape and 

 rugose sculpture. The costulse are generally irregular and vermic- 

 ulate, but even when nearly straight, they always bifurcate at the 

 periphery. Large coarsely sculptured specimens are called by 

 Pfeiffer and authors H. lamellicosta (vide fig. 15). But this form is 

 not even varietally distinct. Several specimens before me do not 

 exceed 20 mill, in diam.; this small form is usually less rugose than 

 the types, but may be known by the bifurcating costulse, and the 

 conformation of the basal lip, which is also a very constant charac- 

 ter, never being notched or truncate at the outer base as in H. 

 guantanamensis, a species of similar depressed, oblong form and 

 inhabiting the same districts. 



Section PARTHENA Albers. 



Parthena ALB., Die Heliceen, p. 112 (1850.) Leiostoma SWAINS. 

 MalacoL, p.. 328, 1840 (not Leiostomus Lacepede, Hist. Nat. Poiss. 

 iv, p. 439, 1802.) Helicogena FER., in part. Eurycratera BECK, 

 Index, p. 45. (1837) in part ; and of most authors. Leiocheila 

 ALBERS, Die Heliceen, p. 109 (type H. jamaicensis) Liochila v. 

 MART., 1. c. ed. 2, p. 146. (1861). 



The synonymy of many subgeneric names of Helices is involved 

 in almost inextricable confusion ; and the case under consideration 

 is probably as intricate as any. The generally-accepted name, 



