NATURAL SCIENCES OF PHILADELPHIA. 245 



S3'stcma sexuale simplex ; desuut sagitta, bursa, flagx'llum, et vesica 

 mullifida. Orificium lit in Ilelice positum. 



Externally, the animal resembles that of Helix. It is bluish- 

 slate colored. 



"We have already described and figured tlie lingual dentition 

 (see Am. Journ. Conch., VII. 190, i)l. 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 Arionla. 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 onl}' 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 CAjiPESTKis, 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, I.e.). 

 SucciNEA LiNEATA, W. G. Bian. 



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 moUusks, mostly terrestrial, we here 

 propose to review our work, to see how nearlj'- our observations 

 agree with the generic descriptions published b}^ 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 I. II. and 



' See our plate, fig. 3. There is oue accessary organ, of use unknown to 

 us. See below, explanation of plate. 



