a 
x 
Dentition of Pulmonate Mollusks. 123 
Lingual membrane (PI. XII, fig. I) as in Bul. Bahamensis; the transverse 
rows of teeth in this type of membrane are waving. 
Mormus suffiatus, Gld. 
Jaw as usual in Bulimulus ; about 21 ribs. 
Lingual membrane as in B. chrysalis. 
Mormus Jonasi, Pfr. 
Jaw as usual in Bulimulus. 
Lingual membrane as Bb. Bahamensis, 
Scutalus rhodolarynx, Rve. Northern Peru. Prof. Orton. 
Jaw ruined by the action of potash. 
Lingual membrane (Pl. XII, fig. D) as in B, chrysalis ; long and narrow ; 
teeth 40-1-40. 
Scutalus proteus, Brod. Northern Peru. Prof. Orton. 
Jaw as usual ; 28 ribs. 
Lingual membrane as in B. altoperuvianus. 
Leptomerus limneoides, Fer. St. Kitts. Dr. Branch. 
Jaw (Pl. XVI, fig. I) low, wide, semitransparent, slightly arcuate, ends 
scarcely attenuated, blunt ; anterior surface with about sixteen ribs, denticu- 
lating either margin. It is extremely difficult to decide upon the character 
of these ribs. Some appear to be a simple thickening of the jaw, formed by 
the overlapping of distinct separate plates. Others remind me of the distant 
narrow ribs of most of the Bulimul, of the character of the ribs in Cylindrella, 
etc. At other points upon the jaw there seem to be broad, flat ribs with 
narrow interstices. 
Lingual membrane long and narrow (Pl. XII, fig. E). Teeth as usual in 
the Helicinw. The change from laterals to marginals is very gradual, the 
latter being but a modification of the former, with two cutting points, the 
inner the longer. Thus it appears that this species in its dentition agrees 
with B. cinnamomeo-lineatus, pallidior, chrysalis, dealbatus, Guadalupensis, alter- 
ndtus, sporadicus, solulus. sepulcralis, durus, Peruvianus, rhodolarynx, and not 
with Jaticinctus, Bahamensis, auris-leporis, papyraceus, Jonasi, membranaceus, 
trigonostomus, flavidus, virgindlis, conveeus, Vincentinus, Lobbi, allernans, multi- 
fuscialus, primularis. 
Teeth 80-1-30, with about ten laterals on each side. The outer cutting 
point of the marginals is sometimes bifid. 
