Dentition of Pulmonate Mollusks. 125 
tant, delicate, oblique ribs, serrating either margin, those of the 
upper centre meeting or ending before reaching the lower 
marein. 
Lingual dentition quite peculiar. As Messrs. Crosse and Fis- 
cher, in their exhaustive paper (Journ. de Conch., XVIII, Jan., 
1870), have indicated the different types of dentition found in 
the genus, I have referred to their respective groups the various 
species I have examined. 
Group A.—Two lateral teeth on each side of the median line; 
marginals of a different form, varying in number. 
Cylindrella (Casta) Chemnitziana, Fer.’ Jamaica. 
There are 10-1-10 teeth; two laterals on each side. 
Cylindrella cyclostoma, Pfr. (Trachella.) Lomas de Camoa, 
Cuba. Mr. Arango. 
Jaw with over 70 ribs. 
Lingual membrane with 16-1-10 teeth, two being laterals on either side; 
the first marginal is a modification of the laterals, other marginals of usual 
long and narrow shape, upper margin reflected. 
Cylindrella Humboldtiana, Pir. Cuba. Mr. Arango. 
Jaw with over 100 ribs. 
Lingual membrane with 8-1-8 teeth, as in C. rosea, figured by Crosse and 
Fischer. The species belongs to their group 7haumasia. 
Cylindrella rosea, Pfr. (Urocoptis.) 
Jaw photographed in Am. Journ. Conch., V, p. 87. 
Cylindrella subula, Fer. (Mychostoma.) Jamaica. Mr. H. 
Vendreyes. | 
Lingual membrane with 10-1-10 teeth, as in C. gracilis, figured by Crosse 
and Fischer. Lower margin of hase of attachment of laterals delicately 
fringed or crimped; marginals 8, long, laminar, with irregularly recurved 
apices. 
Cylindrella seminuda, Ad. (Mychostoma.) Jamaica. Mr. 
Gloyne. 
Lingual membrane as in last species. 
rroup C.—Lateral teeth more than two; marginal teeth simi- 
lar to, and not to be distinguished from, the laterals. 
