178 AMERICAN JOURNAL 



Lingual membrane Ion"; and narrow ; teeth as usual in the 

 genus ; the long cusp of the centrals and laterals sharply pointed ; 

 marginals wide, low, irregularly denticulated ; denticles usually 

 long, oblique, trifid, the central point the longest. 



San Domingo. Dr. W. Newcomb. 



Helix diaphana, Lam. (Plagioptycha.) 



Jaw thin, slightly aicuate, of almost equal height throughout ; 

 ends blunt, cutting edge with a slightly developed, blunt, me- 

 dian projection. 



Lingual membrane as usual in the genus ; marginal teeth with 

 one broad, oblique, long, obtusely trifid denticle. 



Puerto Rico. From Dr. Cleve. 



Helix monodonta, Lea. [Plagioptycha.) 



Jaw thin, light horn colored, but slightly arcuate; ends but 

 little attenuated, blunt ; anterior surface without ribs; cutting 

 edge with a slightly developed, median projection. 



Lingual membrane as usual in the genus ; marginal teeth 

 usually with three oblique, long denticles, the inner the longest. 



San Domingo. Dr. Newcomb. 



Helix graminicola, Adams. (Polymita). 



Jaw strongly arcuate, stout, rough, high ; ends scarcely at- 

 tenuated, blunt ; no anterior ribs ; cutting edge with a decided, 

 blunt, broad, median projection. 



Lingual membrane with about 40 — 1 — 40 teeth in each row ; 

 teeth as usual in the genus ; centrals tricuspid, laterals bicuspid, 

 marginals broad, low, with two stout bifurcated denticles, or, 

 at the extreme edge of the membrane, with simply three obtuse 

 denticles, of which the central is the longest. 



Jamaica. Messrs. \ r endryes and Gloyne. 



It will be seen from the above description that this specie.^ 

 has a jaw similar to that of Helix varians, in the important 

 characteristics of absence of ribs on its anterior surface, and 

 presence of the median projection to the cutting edge. Both 

 species belong to the Section Polymita. Helix muscarum, be- 

 longing to the same section, has already been described by us as 

 having a rough, coarse jaw, without ribs on its anterior surface. 

 It has, however, no median projection to its cutting edge. (See 

 Am. Journ, Conch., 1871. PI. 16). 



Pfeiffer places this species in the synonymy of H. gilva, For., 

 as to the correctness of which we entertain some doubt. 



Helix macroglossa, Pfr., and Helix albersiana, Pfr., have 

 also the same style of jaw as H. varians and H. graminicola. 



