HELIX-OX YCHONA. 131 



I have not seen this species. Pfeiffer says that it is very rare, and 

 that he has seen none besides an excellent specimen in the Menke 

 collection and one presented to him by Menke. The species is 

 readily distinguished from H. bifasciata by its depressed form, pitted 

 keel, and the deflection of the last whorl at the aperture. H. bifasciata 

 also has a somewhat pitted-crenate malleation of the last whorl, 

 close above and below the central keel. 



H. GYRINA Valenciennes. PI. 57, figs. 26, 27. 



Imperforate, elevated-conical, rather thin, subregularly striate, 

 and (under a strong lens) decussated with close spiral strise, 

 diaphanous, whitish ; spire conical, apex acuminate ; whorls 6J, 

 nearly flat, the last acutely carinated, scarcely descending anteriorly ; 

 base a little convex ; aperture very oblique, subquadrangular ; per- 

 istome a little thickened within, white, the right margin somewhat 

 flexuous, rather widely expanded ; basal margin reflexed, columellar 

 margin adnate a short distance. 



Alt. 13, diam. maj. 13J, min. lit mill. (Pfeiffer.) 



Brazil. 



Helix gyrina VAL. (in Paris Mus.), DESK, in Fer., Histoire, t. 

 63B, f. 4. PFEIFFER, Monographia iii, p. 180; iv, 204; v, 273. 



This, too, is a rare form, which I have not seen. Pfeifler's 

 description, drawn from a specimen in the Cuming collection, is 

 translated above. 



H. PILEIFORMIS Moricand. PI. 57, fig. 31. 



Narrowly perforate, elongated-trochiform, thin, subtransliicent, 

 whitish or olivaceous-brown, obliquely closely striate, and under a 

 lens seen to be spirally finely marked by close impressed lines ; spire 

 elevated, pyramidal; apex blunt; first two whorls con vex, separated 

 by deep sutures, and densely longitudinally costulate striate; following 

 whorls less convex, nearly flat, separated by linear sutures ; last 

 whorl acutely angulated in the middle, slightly convex beneath, not 

 descending anteriorly ; aperture subquadrate, oblique; outer lip some- 

 what expanded, basal lip expanded ; columella straight, vertical, 

 expanded and appressed half around the narrow umbilicus. 



Alt. 17, diam. 12J mill. ; alt. 14, diam. 12 mill. 



Brazil. 



Helix pileiformis MORIC. in Mem. Soc. Geneve, vii, p. 420, t. 2, f. 

 2. LAMARCK, An. s. Vert., ed. Desh., p. 134. PFEIFFER, 

 Monographia i, p. 323 ; Conchyl. Cab., p. 318, t. 55, f. 9, 10. Bull- 



