Dentition of Pulmonate Mollusks. 123 



Lingual membrane (PI. XII, tig. I) as in Bui. Bahamensis; the transverse 

 rows of teeth in this type of membrane are waving. 



Mormus sufflatus, 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 B. Bahamensis. 



Scutalus rhodolarynx, Eve. Northern Peru. Prof. Orfcon. 



Jaw ruined by the action of potash. 



Lingual membrane (PI. XII, fig. D) as in B. chrysalis ; long and narrow ; 

 teeth 40-1-40. 



Scutalus proteus. Brod. Northern Peru. Prof. Or ton. 



Jaw as usual ; 28 ribs. 



Lingual membrane as in B. altoperuvianus. 



Leptomerus limnceoides, Fer. St. Kitts. Dr. Branch. 



Jaw (PI. XVI, fig. I) low, w T ide, 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 Bulimuh, 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 V P1. XII, fig. E). Teeth as usual in 

 the HeUc'mce. 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. cimiamomeo-lineatus, pallidior, chrysalis, dealbahts, Guadalvpensis, alter- 

 nalus, sporadicvLS, solulus. sepulcralis , durus, Peruvianus, rhodolarynx, and not 

 Avith laticinctus, Bahamensis, auris-kporis, papyraceus, Jonasi, membranaceus, 

 trigonostomus, flauidus, oirgincdis, coaoexas, Vincentinus, Lobbi, allernans, mnlti- 

 fascialus, primularis. 



Teeth 30-1-30, with about ten laterals on each side. The outer cutting 

 point of the marginals is sometimes bifid. 



