122 Dentition of Pulmonate Mollusks. 
Liostracus alternans, Beck. Islands in the Bay of Panama. 
Mr. McNeil. 
Jaw as usual in the genus, 52 ribs. 
Lingual membrane as in last species. 
Lniostrucus Marielinus, Poey. 
See Terr. Moll., V. 
Mesembrinus primularis, Rve. Northern Peru. Prof. Orton. 
Jaw as usual in the genus. 
Lingual membrane (Pl. XII, fig. G) as in last species, but there is only 
one cutting point in the central tooth. 
Mesembrinus pallidior, Sowb. 
See Terr. Moll., V. 
Lingual membrane as in the following, not as in last species. 
Mesembrinus chrysalis, Pfr. Martinique. Gov, Rawson. 
Jaw of the type common in bulimulus, Cylindrella, etc., arcuate, low ; ends 
blunt ; thin, transparent ; with eighteen narrow, separated ribs; a trans- 
verse central line of reinforcement. Attached to the upper margin is a strong 
triangular membrane of the same consistence 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 Succinee. (Pl. XV, fig. Q.) 
Lingual membrane (Pl. XIV, fig. G) as usual in the Helicine. Centrals 
about as broad as long, tricuspid, and 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. 
Thaumastus immaculatus, Ad. Jamaica. Mr. Gloyne. 
Jaw as usual in Bulimulus ; over 36 ribs. | 
Lingual membrane (Pl. XII, fig. H) as in Bul. chrysalis ; central teeth with 
three cutting points. 
Mormus membranaceus, Phil. Brazil. J. G. Anthony. 
Jaw as usual ; with about 24 ribs. 
Lingual membrane as in Bul. chrysalis. 
Mormus laticinctus, Guppy. Dominica. Mr. Guppy. 
Jaw not examined. 
