88 HELIX-STYLODONTA. 



upon the last whorl the suture becomes deeply impressed, the whorl 

 convex above and below, descending a little below the periphery in 

 front. Aperture very oblique, rounded-lunate, white or flesh-colored 

 inside ; the entire peristome rather broadly reflexed, white ; columella 

 convex on its inner edge, deeply, vertically inserted ; parietal wall 

 washed with transparent callus. 



Alt. 40, greater diani. 62, lesser 51 mill. 



Alt. 36, greater diam. 51, lesser 43 mill. 



Island of Praslin, Seychelles. 



Helix (Helicostyla) Studeriana FER., Histoire, 1. 103, f. 6. PFR., 

 Symbolse i, p. 36 ; Monographia i, p. 243 ; Conchylien Cabinet, t. 

 41, f. 1, 2.Stylodon Studeriana BECK, Index, p. 46.Nanina (Sty- 

 lodonta) Studeriana Fer. TRYON, Manual of Conchology, 2d. Ser., 

 vol. ii, p. 26. Helix Studeriana Fer. KEEVE, Conch. Icon., t. 39, f. 

 153. DUFO, Obs. sur les Moll, marins, terrestres et fluviatiles des 

 iles Seychelles et des Arnirantes, in Annales des Sci. Nat., 2d Ser., 

 vol. xiv, p. 199. STEENSTRUP, Om Ovo-vivipariten hos Helix Stu- 

 deriana, etc., in Videnskabelige Meddelelser 1879-80, p. 301. 

 VIGUIER, Obs. sur la viviparite de 1'Helix studeriaua Fer., in Arch, 

 de Zool. Exper. et Generate viii, 1879-80, p. 529, plate 40. 



A large species having much the aspect of H. illustris Pfr., but 

 readily distinguishable by the beautifully clear-cut granulation of 

 the upper whorls and the short almost vertical columella. The 

 young shells are acutely keeled. It is an ovo-viviparous species, as 

 Dufo observed as long ago as 1840. 



The abrupt change in surface-sculpture which takes place at birth 

 is shown in the enlarged detail-drawing, pi. 61, fig. 18. 



Dufo says : " Inhabits the mountain tops, on bushes and lianas. 

 Feeds upon green leaves. Movements slow." 



Subgenus XIX. CAM^ENA Albers, 1850. 



The name Camcena may be used in an extended sense, to include 

 a number of sections containing most of the larger helices of the re- 

 gions lying between Japan on the north and Australia on the south. 

 Until more knowledge of the soft parts is obtained,, it is impossible 

 to indicate the rank and classification of the several minor groups 

 with certainty. In the formation of sections I have not hesitated to 

 discard certain characters heretofore used for this purpose, in favor 

 of new and original ones. This course has inevitably led me to 

 change the limits and contents of the groups of previous authors. 



