HELIX. 183 



39. HELIX TRIDENTATA, SAT. 

 Plates XXVII. XXVIII. 



H. testa depressa, profunda 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 armatd.. 



SYNONYMS AND REFEEENCES. 



Helix tridentata. Say, Nich. Encyc. IV. pl. 2, f. 1. 



Ferhssac, Tab. Syst. 38 ; Hist. pl. 51, f. 3. 



Wood, Ioc. cit. Supplem. pl. 7, f 2. 



Deshates, Encyc. Meth. II. 213. 

 in Lamarck, VIII. 115. 



KiRTLAND, Ohio Report. 



Sager, Micliigan Catalogue. 



BiNNEY, Boston Journ. Nat. Hist. III. 3S2, pl. 17 & 18. 



De Kay, New York Report, 31. 



Adams, Vermont Mollusca, 10. 



Gould, Invertebrata, 173, f. 115. 



Chemnitz, 2d ed. pl. 10, f. 7, 8. 



Pfeiffer, Monog. Helic. Viv. I. 412. 

 Hdix foDax, Say, Journ. Acad. II. 119. 



Chemnitz, 2d. ed. pl. 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, tenninatiug in an acute 

 angle. 



Shell depressed, a little convex ; epidermis varying 

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



