74 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



species are known to occur in Haiti. It is practically certain 

 that Weinland did not see all of the teeth, only the angulo- 

 parietal and upper palatal being noticed by him. There must 

 certainly be a columellar lamella, and I suspect lower palatal 

 and basal plicae also, though these might be degenerate, as in 

 G. s. riisei. 



2la. G. servilis riisei (Pfeiffer). PL 14, figs. 8, 9. 



The shell differs from G. servilis by the oblong, less conic 

 shape ; the teeth are smaller ; the parietal lamella is lower ; a 

 basal fold is absent, and the upper palatal plica is small or 

 often wanting. Length 2.2, diam. above aperture 1 mm. 

 Otherwise like G. servilis. 



The series examined comprises 9 specimens from St. 

 Thomas (Henderson collection, from that of Prof. Theo. Gill), 

 and 20 from Water Island, near St. Thomas (Academy coll.,. 

 from Thomas Bland). By the thin lip, color, etc., it seems to 

 be a local derivative of the widespread G. servilis, comparable 

 to G. p. parvidens Sterki, a much smaller shell. By the weak- 

 ness of the upper palatal and basal plicse it resembles the 

 form described as oblonga Pfr., but that is much paler in 

 color, and probably to be looked upon as a parallel modifica- 

 tion of servilis. 



I presume that this form is Pfeiffer 's riisei, which was de- 

 scribed as follows : 



Pupa riisei. Shell subrimate, ovate-cylindric, thin, most 

 minutely striate, somewhat glossy, pellucid, pale corneous; 

 spire gradually tapering, the apex obtuse; suture simple; 

 whorls 5, convex, the last one-third the length, rounded at 

 base; columella subplicate; aperture slightly oblique, oval- 

 oblong, toothless ; peristome thin, narrowly expanded through- 

 out. Length 2.5, diam. 1 mm., aperture scarcely 1 mm. long 

 (Pfr.). 



St. Thomas, type loc., and Porto Rico (Riise). 



Pupa riisei PFR., Zeitschr. f . Malak., 1852, p. 151 ; Monogr. 

 Hel. Viv., iii, p. 532; iv, 684, as var. of pellucida. ? Pupa 

 riisei Pfr., KUESTER, Syst. Conch. Cab., p. 178, pi. 21, f . 13, 14. 



Pfeiffer considered P. riisei a variety of P. pellucida in the 



