HELIX. 183 



39. HELIX TRIDENTATA, SAY. 



PLATES XXVII. XXVIII. 



H. testa depressa, profunde umbilicata, corneo-rufescente ; 

 anfractibus striatis, striis distinctis, crebris, obliquis ; aper- 

 tura contracta, trilobata ; labro albo, reflexo, dentibus duo- 

 bus instructo ; columella dente albo sub-arcuato armata. 



SYNONYMS AND REFERENCES. 



Hdix tridentata, SAY, Nich. Encyc. IV. pi. 2, f. 1. 



FERUSSAC, Tab. Syst. 38; Hist. pi. 51, f. 3. 



WOOD, loc. cit. Supplem. pi. 7, f. 2. 



DESHAYES, Encyc. Meth. II. 213. 

 in Lamarck, VIII. 115. 



KIRTLAND, Ohio Report. 



SAGER, Michigan Catalogue. 



BINNEY, Boston Journ. Nat. Hist. III. 382, pi. 17 & 18. 



DE KAY, New York Report, 31. 



ADAMS. Vermont Mollusca, 10. 



GOULD, Invertebrata, 173, f. 115. 



CHEMNITZ, 2d ed. pi. 10, f. 7, 8. 



PFEIFFEB, Monog. Helic. Viv. I. 412. 

 Hdix fallax, SAY, Journ. Acad. II. 119. 



CHEMNITZ, 2d. ed. pi. 64, f. 7-9. 

 PFEIFFER, Monog. I. 412. 

 KIRTLAND, SAGER, DE KAY, ut supra. 



DESCRIPTION. 



ANIMAL dark bluish slate color, deeper on the head 

 and tentacles ; length of superior tentacles about a quar- 

 ter of an inch ; foot narrow, equal in length to nearly 

 twice the diameter of the shell, terminating in an acute 

 angle. 



SHELL depressed, a little convex ; epidermis varying 

 from light corneous, or russet, to chestnut ; whorls four 



