16 HELIX PLAGIOPTYCHA. 



moderate, infundibuliform ; aperture very oblique, lunate-oval, 

 shining within ; peristome thin, margins approximating, the superior 

 one deeply curved, a little expanded, base margin briefly reflexed, 

 with an oblique fold within. 



Alt. 7, diam. maj. 16J, min. 131 mill. (Pfeiffer}. 



Hayti. 



H. strumosa PFR. P. Z. S. 1852, p. 139 ; Conchyl. Cab. p. 478, t. 

 158, f. 25-27 ; Monogr. in, p. 243. REEVE, Conch. Icon. f. 763. 



I have not seen this species. It may be known by the gibbous and 

 constricted whorl behind the aperture, and the umbilicated base. It 

 may perhaps prove to have more affinity with H. santacruzensis and 

 H. phsedra than with the species with which it is here grouped. 



H RIISEI Pfeiffer. PL 11, figs. 33, 34. 



Imperforate, conoid-depressed, rather solid; smooth, whitish, sub- 

 diaphanous, encircled by a single reddish line; spire very short, 

 conoid: whorls 4?, scarcely convex, the last depressed-rotund, sensi- 

 bly descending anteriorly ; aperture very oblique, sub-lunar ; peri- 

 stome sublabiate, the margins subparallel, right lip slightly expand- 

 ed, columella flat, with a compressed, transverse fold within. 



Alt. 8i, diam. 15 mill. (P/r.) 



Ins. Vieque. 



H. riisei PFR. Mai. Slat, iii, 1856, p. 44 ; Novit Conch, i, p. 77, t. 

 21, f. 13, 14. 



H. PLATONIS Pfeiffer. PL 19, figs. 48-50. 



Very narrowly umbilicate, depressed-turbinate, thin, finely costu- 

 late-striate, scarcely shining, diaphanous, corneous-isabella colored ; 

 spire conoid, apex rather acute, blackish, shining ; suture deep, 

 submarginate ; whorls 5, convex, the last encircled by two brownish 

 lines, deeply descending anteriorly, flatter beneath, subconstricted 

 anteriorly ; aperture very oblique, lunate-oval ; peristome thin, the 

 margins scarcely converging, the right margin a little expanded, 

 basal and columella margins much dilated, reflexed, with a denti- 

 form oblique callus within. 



Alt. 7, diam. maj. 12, min. 10* mill. (Pfeiffer}. 



ML Plato, Hayti. 



H. platonis PFR. Malak. Bl. 1866, p. 81 ; and Monographia, v, 

 p. 355. 



Three specimens of this form, in poor condition, are before me. 

 They are distinguished from the variable H. indistincta by the more 



