82 NEW-YORK FAUNA — MOLLUSCA. 



{EXTRA-LIMITAL.) 



FAMILY CYCLOSTOMinM. 



Animal loithout a collar, and with two tentacles eyed at their external bases. Shell conoid, more 

 or less elevated, with the aperture rounded, and with its margin continuous. 



Genus Cyclostoma, Lam. Animal very spiral, with a proboscis-like head bearing two cylindrical 

 tentacles, swollen at their tips, contractile and eyed at their external bases. Foot oblong, 

 elongated. Pulmonary cavity communicating externally by a large fissure in the upper and 

 anterior part of the mantle. Place of the male organ indicated by a large tentacular appendix 

 on the right side, and reflected into the pulmonary cavity. Shell conoid, discoid or turreted, 

 more or less elevated. Aperture circular, entire, and in the adult reflected. Opercle calca- 

 reous, increasing concentrically : summit subcentral. 

 C. dentata. (Say, Ac. Sc. Vol.5, p. 125.) Shell conic, cylindric, truncate at tip. Whorls 3 -4, 



slightly convex, cancellate with fine regular subequal longitudinal and transverse elevated lines; 



superior edge fimbriated, with prominences extending over the suture; lip somewhat reflected; 



umbilicus distinct. Co/or, rufous; revolving lines occasionally obsolete ; lip white. Height, 0-4. 



Florida. 

 C. cincinnatiense. (Lea, Am. Phil. Tr. Vol. 8, p. 229, pi. 6, fig. 62. A. sayana? Anthony.) 



Shell elevated in the form of a cone, smooth, shining, transparent, umbilicate. Whorls 6; apex 



obtuse; margin of the lip reflected. Length, 0-22; diameter, 0- 13. Cincinnati. 



FAMILY HELICINID^. 



Animal with a collar ; two filiform tentacles, with eyes at their external bases on tubercles. Shell 

 more or less globular ; aperture entire, semioval ; columella transverse and flattened ; opercle horny. 



Genus Helicina, Lam. Animal with a bilabiate muzzle; foot short, rounded, with a transverse 

 furrow in front. Pulmonary cavity opening in front of the mantle by a large transversal 

 furrow. iSAe// subglobular, slightly depressed, not umbilicated; spire low; columella callous; 

 margin of outer lip acute, forming an angle at the base of the right margin. 



H. orbiculata. (Say, Am. Conch, pi. 46, fig. 1-3.) Subglobular; spire not very prominent, but 

 more than convex. Whorls five, obsoletely striated across, regularly rounded ; base of columella 

 very slightly projecting into an obtuse angle ; lip reflected. Color, pale greenish, yellowish or 

 slightly reddish, margined above by a paler line ; occasionally a pale revolving band on the body- 

 whorl. Florida. ' 



H. fastigiata. (Id. Des. terr. & fluv. shells, p. 14.) Whorls compressed, acutely carinated ; beneath 

 the carina, the elevated lines obsolete. Lip two-toothed ; the lower conic, obtuse. Diameter, 0- 35. 

 Illinois. 



H. plicata. (Id. 1. c. p. 14.) Inferior tooth compressed, and larger than the other; duplicature of 

 the labium emarginate near the tip. Closely allied to the preceding. 



H. occulta. (Id. 1. c. p. 15; Am. Conch, pi. 46, figs. 4, 6.) Whorls five, carinate, or with an 

 acute shoulder, which is almost concealed on the spire by the suture, and almost obsolete on the 

 body-whorl, which latter has faint revolving lines. Lip thick, a little reflected. Western Slates. 



