352 HELIClNADiE. 



Trochidre. Mr. Gray makes a family exclusively for 

 them, ■v\hicli he calls Oligyradge ; but it would not seem 

 that their anatomical characters are siifEciently diverse 

 from those of Cyclostoma to justify a separation. — [g.] 



1. HELICINA ORBICULATA, Say. 



Plate LXXIII. LXXIV. Figuke 3. 



H. testa parva, sub-globosa, solidula, tenuissime striata 

 flavescente, cinerascente, vel rufescente, plerumque ad peri- 

 pheriam albo-zonata ; spira anfractibus quinque, convexis ; 

 apertuva lunata ; labro reflexiusculo, albo, incrassato, junc- 

 tione cum columellam dentiformi. 



SYNONYJIS AND EEFERESCES. 



OUgyra orbiculala, Say, Journ. Acad. Nat. Sc. I. 2S3, May, ISIS ; 



Nicholson's Eiicycl. IV. ; 



American Conchulog-y, pi 46, figs. 4, 5, 6. 

 Helicina orhiatlata, Gray, Zool. Journal, I. 70. 

 Helicina riibeUa, Green, Douglily's Cab. Nat. Hist. II. 291, anno 1S33. 



DESCRIPTION". 



Animal. Head and tentacles black, the other parts 

 of the body dark. Tentacles long and slender, tapering 

 to a pomt. Eyes black and prominent. Motion gliding 

 as in Helix. Operculum horny, turning back upon the 

 columella as if upon a hinge. 



Shell. Shell sub-globose, acute at ape.x, solid, 

 smooth, very delicately striated ; color yellowish, brown- 

 ish, or ash-colored, with a linear, pale zone at the peri- 

 phery, which passes up the spire at the suture, and 

 makes it white ; there are also in many specimens 



