Dentition of Pulmonale Mollusks. 9J 



species in which the dentition of muscarum and picta may be 

 looked for. The others will probably agree with varians, etc. 



The jaw of varians, grdlopavonis, Troscheli, rufoapicata, 

 (jr a mini cola, is high, arched, without ribs, with a blunt median 

 projection. In one species, Milleri, the jaw is like this, except- 

 ing that it has one dscided, stout, central rib, denticulating 

 either margin. This shows that the presence or absence of ribs 

 on the jaw cannot be considered a reliable generic character. 

 (See, also, Dentellaria.) 



Hemitrochus varians, Mke. (See Terr. Moll., V.) 



Hemitrochus Troscheli, Pfr. New Providence, Bahamas. 

 Gov. Eawson. 



Jaw as described ; a strong, transverse line of re-enforcement. 



Lingual membrane (PI. IV, fig. A) long and narrow. Central teeth very 

 long ; the upper margin of base of attachment greatly produced above ; the 

 reflected portion not extending to the lower margin; median cusp with a 

 short, blunt cuttiug point; side cusps and cutting points obsolete. Laterals 

 like the centrals, but asymmetrical ; the upper margin still more produced ; 

 outer laterals with bifid inner cutting point, and side cusp and cutting point. 

 Marginals quadrate, with one large, oblique, rounded, bluntly bifid cutting 

 point, and one or two side, small, blunt cutting points. The membrane is 

 peculiar in the extension of the upper margin of the base of attachment of 

 the teeth. 



Hemitrochus gallop airo?iis,Yal. Turk's Island. G-ov. Rawson. 



Jaw as- described. 



Lingual membrane as described in last species. (PI. IV, fig. B.) 



Hemitrochus rufoapicata, Poey. Cuba. Mr. Arango. 

 Jaw and lingual membrane (PI. IV, fig. C) as described above. 



Hemitrochus graminicola, Ad. Jamaica. Messrs. Vendreyes 

 and Gloyne. 



Jaw as described. 



Lingual membrane (PI. IV, fig. E) as described. Teeth 40-1-40. 



Of the above species, the figure gives one central, the adjacent 

 lateral or laterals, and one or more marginals. 



Hemitrochus Milleri, Pfr. Fortune Island, Bahamas. Dr. 

 J. J. Brown. 

 Jaw differing from that of the above species by the presence of a stout, 



