NATURAL SCIENCES OF PHILADELPHIA. 245 
Systema sexuale simplex ;! desunt sagitta, bursa, flagellum, et vesica 
multifida. Orificium ut in Helice positum. 
Externally, the animal resembles that of Helix. It is bluish- 
slate colored. 
We have already described and figured the lingual dentition 
(see Am. Journ. Conch., VII. 190, pl. xvii. fig. 3, 4). The jaw 
is long, low, slightly arcuate; ends blunt; anterior surface with 
about sixteen stout, separated ribs, scalloping either margin. 
The jaw is lower, less arcuate and longer than in Arionta. Its 
ribs resemble those of that subgenus in projecting far beyond and 
scalloping the margins of the jaw, but they are much more 
numerous. 
This description applies only to the more perfect form of the 
jaw (fig. 1 of our plate), noticed only in one individual. In several 
other individuals the ribs on the jaw were much more narrow and 
less projecting at the upper and lower margins. There is more 
difference between these than is usually found in different indivi- 
duals of the same species. 
SUCCINEA CAMPESTRIS, Say. 
Charleston, S.C. Mr. W. G. Mazyck. 
Jaw as usual in the genus; the anterior surface has no decided 
ribs. 
Lingual membrane as usual in the genus (see our figure on p. 
267, Ik @5}}6 
SUCCINEA LINEATA, W. G. Binn. 
Little Colorado River, Arizona. Dr. E. Palmer. 
Jaw and lingual membrane as usual in the genus, the former 
without distinct anterior ribs. 
Having published many descriptions and figures of the jaws 
and lingual dentition of mollusks, mostly terrestrial, we here 
propose to review our work, to see how nearly our observations 
agree with the generic descriptions published by Albers and von 
Martens for the various genera. We give below a list of our 
descriptions published previous to 1873 in other works than the 
Land and Fresh-water Shells of North America, Parts IJ. II. and 
! See our plate, fig. 8. There is one accessary organ, of use unknown to 
us. See below, explanation of plate. 
