204 AMERICAN JOURNAL 



of land mollusks has vsoraetimes the longitudinal striae extending 

 from the jaw itself, but, as far as noticed by us, this muscular 

 attachment is simply an extension of the upper margin of the 

 jaw itself, while in Helix tumida the projection springs from a 

 different part of the jaw. 



Helix aspera, Fer. 



The specimen examined was received from Jamaica. 



Jaw long, narrow, arcuate, of almost equal width throughout ; 

 ends blunt, but slightly attenuate ; anterior surface with eight 

 sharp, prominent, conspicuous ribs, strongly denticulating both 

 margins. 



Lingual membrane long and narrow, composed of numerous 

 rows of about 41 — 1 — 41 teeth each. Centrals and laterals as 

 usual in the genus. The upper edge of the plate of the centrals 

 is decidedly divided into two equal lobes. In the laterals the 

 same edge is straight, but narrower than the centre of the tooth. 

 Uncini subquadrate, with one large short denticle, with a bluntly 

 tricuspid point. 



Helix acuta, Lam. 



The specimen figured was received from Jamaica. 



Jaw arched, thick, long, narrow, of almost uniform width 

 throughout, ends attenuated, blunt; anterior surface with seven 

 distant, stout ribs, denticulating both margins. 



Lingual membrane long and narrow, composed of numerous 

 rows of about 40 — 1 — 40 teeth each. Centrals and laterals as 

 ttsual in the genus. Uncini with apparently only one long, ob- 

 lique denticle. 



Helix muscarum, Lea. Plate 9, figs. 4 and 16. 



Jaw long, narrow, arched, delicately striated ; ends attenuated, 

 bluntly rounded ; no trace of anterior ribs, and no median pro- 

 jection to the cutting edge. See fig. 16, 



Lingual membrane long and narrow, composed of numerous 

 rows of about 75 — 1 — 75 teeth each. These rows are arranged 

 en chevron, quite as much so as in the genus Cylindrella. Cen- 

 trals long, narrow, curving inwards at the sides, so as to make the 

 centre of the plates the narrowest part. The upper edge of the 

 plates is slightly rounded. The lower edge is trilobed. The 

 cutting cusp is placed at about one-fourth the distance from the 

 lower to the upper edge of the plate. It is strongly trilobed, 

 each lobe extending into a long, broad, stout, blunt denticle. 

 The denticles do not extend beyond the lower edge of the plate. 

 They are often much more broadly expanded than in the tooth 

 figured. The central teeth are symmetrical. The laterals are 



