242 PROCEEDINGS OF THE ACADEMY OF 



Jaw with about ten ribs ; as usual in the subgenus.^ 

 Lingual dentition as usual.* 



Helix fallax, Say. ( Triodopsis. ) 



Philadelphia, Miyiroe Co., Tenn. Miss Annie E. Law. 



Lingual membrane and jaw as usual in Triodopsis,^ the latter 

 with about fourteen ribs. 



Helix tridentata, Say. {Triodopsis.) 

 Same locality as last. 



Jaw as usual in the subgenus.^ 



Lingual membrane already figured by us. (1. c. fig. 220, p. 130.) 



Helix Hopetonensis, Shnttlewortli. ( Triodopsis. ) 

 Charleston, S. C. Mr. W. G. Mazyck. 

 Jaw with over ten ribs ; as usual in the subgenus.'' 

 Lingual membrane as usual. 



Helix dentifera, Binney. (Mesodon.) 

 Mohawk, New York. Dr. James Lewis. 

 Jaw with fourteen ribs ; as usual in the subgenus.^ 

 Lingual membrane as usual.^ The marginal teeth remind us of 

 those of Helix thyroides (1. c. p. 148, fig. 252), but the inner den- 

 ticle is more obtusely pointed. The figui'e referred to is liable to 

 mislead. The marginals are subquadrate (not aculeate), with one 

 long, oblique, sharply pointed denticle, much more produced than 

 usual in the genus. 



Helix Roemeri, Pfr. (Mesodon.) 



Bosque Co., Texas. Mr. Hugo W. Ericsson. 



Animal externally as in H. thyroides, dentifera, etc. 

 Jaw and lingual membrane as usual in the subgenus,'^ the former 

 with over seven ribs. 



Helix ELEV ATA, Say. {Mesodon.) 



Philadelphia, Munroe Co., Tenn. Miss Annie E. Law. 



' In Triodopsis the jaw is arcuate, ends blunt, anterior surface with 

 stout, adjoining ribs, which denticulate either margin. See our fig. 214, p. 

 127, 1. c. For lingual dentition, see fig. 215. 



2 In Mesodon the jaw is arcuate, ends blunt; anterior surface with stout, 

 separated ribs, denticulating either margin. See our fig. 231, on p. 137, 

 1. c. The lingual dentition is figured on p. 138, fig. 232. The central and 

 lateral teeth are obtuse, short, stout, with obsolete side denticles to the re- 

 flected cusps. 



