NATURAL SCIENCES OF PHILADELPHIA, 53 



StropMa decumana, Fer. 



Castle Island, Bahamas. 



On pi. VIII., fig. 1, will be found figures of the dentition of this 

 species. For full description, see Annals of Ljc. Nat. Hist, of 

 N. Y., X., p. 348. 



Bulimulus chrysalis, Pfr. 



Martinique. Gov. Rawson. 



Jaw of the t3'pe common in Bulimulus^ Ci/lindrella, etc., arcuate, 

 low; ends blunt; thin, transparent ; with eighteen narrow, sepa- 

 rated ribs ; a transverse central line of reinforcement. Attached 

 to the upper margin is a strong triangular membrane of the same 

 consistency and material as the jaw itself, and equally resisting 

 the action of potash, so as readily to be mistaken for the accessory 

 plate of the Succinese. (PI. Y., fig. 11.) 



Lingual membrane (pi. Y. fig. 12, 13) as usual in the Helicinse. 

 Centrals about as broad as long, tricuspid, the median cusp short 

 and stout, its short point not extending to the base of the plate. 

 Laterals like the centrals, but bicuspid. Marginals wide, low, 

 with one inner, long, blunt, stout, oblique denticle, and one or 

 two short, blunt side denticles. 



Bulimulus Vincentimus, Pfr., var. ? (Drymmus), 



Tobago. Jaw as usual in Bulimulus, CyUndr'ella, etc., thin, 

 transparent, with numerous delicate, separated, narrow ribs. 



Lingual membrane as in Bulimulus taiicinctus, etc. (see Ann. 

 N. Y. Lye, X. pi. xi., fig. 1.) 



Bulimulus Knorri, Pfr. (Drymceus). 



Porto Cabello, Yenezuela, ReeeiA^ed mounted from the late Mr. 

 Robert Swift. 



Jaw arched, high, ends attenuated, blunt ; an obtuse median 

 projection to cutting edge; transverse lines of reinforcement, but 

 uo ribs. 



An unusual form of jaw in this genus, though common in many 

 subgenera of Helix. 



Bulimulus Peruvianus, Brug. (Plectostylus) . 



Talcahuana. Museum Comparative Zoologj^ 



Jaw as in Gylindrella, etc., with about thirty delicate ribs ; 

 upper central plate triangular. 



Lingual membrane (pi. Y., fig. 2) combining tlie usual characters 

 of the genus with those peculiar to the group of B. laticinctus 



