HELIX— Plate LXIII. 



Species 320. (Mus. Adams.) 



Heli.V ambigua. Ilel. testa vix umbilicatd, depreao-orbi- 

 culnri, corned ; spird concexd, suturd impressd ; anfrac- 

 tibm sex, convexis, ultimo rotundato ; aperturd lunari; 

 perutoiiiate tenui, acuta. 



The DoiBTFCL Helix. Shell scarcely umbilicated, de- 

 pressly orbicular, horny ; spire convex, suture im- 

 pressed ; whorls six, convex, the last rounded ; aper- 

 ture lunar ; lip thin, acute. 



Adams, Contributions to Conchology, No. 3. p. 35. 



llai. Jamaica. 



This species appears to be of firmer growth than the 

 preceding, while it is smaller, and has a more confined 

 umbilicus. 



Species 321. (Mus. Adams.) 



Helix Hollasdi. Hel. testa umbilicatd, suidiscoided, 

 corned; spird convexd, suturd impressd ; anfractiius 

 sex, convexis, striatis, ultimo depresso-excavato ; aper- 

 turd lunari ; peristomate simplici, acuta. 



Holland's Helix. Shell umbilicated, subdiscoid, homy; 

 spire convex, suture impressed ; whorls six, convex, 

 striated, the last depressly excavated ; aperture lunar; 

 lip simple, sharp. 



Adams, Contributions to Conchology, No. 3. p. 34. 

 Ilab. Jamaica. 



Chiefly distinguished from the species nearest allied to 

 it by tlie depressly excavated form of the base of the last 

 whorl. 



Species 322. (Mus. Cuming.) 



Helix pila. Ilel. testd ot/tecti perforata, vaI<Q globosd, 

 pellucido-alhd, vitred, nitenle ; spird elatd, apice 

 obtusd; anfractiius sex ad septem, rotundatis, obliqui 

 subtilissiiiii striatis; columella tenui, dilatoio-re^flexd ; 

 aperturd lunari, fauce lamella erectd prominente opaco- 

 aUid instructd ; peristomate tenui, acuto. 



The ball Helix. Shell with a small covered umbilicus, 

 very globose, transparent white, glassy, shining ; 

 spire raised, obtuse at the apex ; whorb sis to seven, 

 rounded, obliquely very finely striated ; coluineUa 

 thin, dilatcly reflected ; aperture lunar, furnished in 

 the interior with an erect prominent opake-white la- 

 mella ; lip thin, shiirp. 



Adams, Contributions to Conchology, No. 2. p. 31. 



Hab. Jamaica. 



An extremely interesting variety of the form represented 

 by the species in the preceding plate, — very globular and 

 of a thin glassy substance. 



