92 PLEURODONTK. 



Shell narrowly umbilicated, rather thin, opaque, hirsute, the spire 

 depressed, body-whorl depressed, rounded at periphery. Aperture 

 as high as wide, trilobate-lunar', peristome narrowly expanded, the 

 outer and basal margins each with one tooth. Type P. auridens 

 Rang, pi. 25, figs. 12, 13. 



Anatomy unknown. The single species inhabits Martinique. It 

 resembles in form H. obvoluta Mull, of Europe. 



Section Caracolus Montf. 



Caracolus MONTF., Conch. Syst. ii, p. 138. PILSBRY, Man. of 

 Conch, v, p. 118. Caraeolla SCHUM., Essai, p. 192, 1817. Serpent- 

 uliis (KLEIN, Tent. Meth. Ostr., p. 8, 1753 ; in part) H. & A. AD., 

 Gen. Rec. Moll, ii, p. 201. Lampadion BOLT, in part. Discodoma 

 SWAINS., Malacol., p. 329, 1840. 



Shell depressed, carinated, imperforate or umbilicate ; thick, solid 

 and opaque ; spire conical, apex obtuse. Whorls 5-6, the last but 

 little or not deflexed in front. Aperture oblique, wider than high ; 

 peristome not toothed, its basal margin expanded or narrowly 

 reflexed, terminations remote. Type P. caracolla L., pi. 25, fig. 1. 



Jaw arcuate, stout, and either smooth with a low median projec- 

 tion (P. caracolla, P. marginella, P. semiaperta), or furnished with 

 stout ribs (P. bornii). See pi. 26, fig. 3, P. marginella', pi. 26, fig. 



6, P. marginella var. rostrata. 



Radula having the central and lateral teeth furnished with a single 

 broad obtuse cusp (coalescent meso-and ectocone). Marginal teeth 

 having an oblique cusp, which is simple as in the lateral teeth, or 

 split into mesocone and ectocone (pi. 26, fig. 8, P. caracolla; fig. 1, 

 P. maginella ; fig. 2, P. marginella var. semiaperta'). 



Genital organs having the vagina more or less swollen, sperma- 

 theca oval, on a rather long (P. caracolla) or a short duct (P. mar- 

 ginella'). Penis long, the retractor inserted at its summit; continued 

 in a long epiphallus which terminates in a short flagellum (pi. 26, fig- 



7, P. caracolla, penis everted ; pi. 26, figs. 4, 5, P. marginella var. 

 rostrata viewed from both sides, the extremely short flagellum seen 

 in fig. 4). 



Distribution : Eastern Cuba ( P. marginella and varieties), Hayti 

 (P. caracolla, excellens, insititia, sarcocheila, angistoma, bizonalis and 

 semiaperta), and Porto Rico and Vieque (P. bornii). 



