HELIX-STYLODONTA. 87 



t. 67, f. 3-5. Helix militaris PFR. Proc. Zool. Soc. Loud. 1855, p. 

 Ill ; Monographia iv, p. 245. 



The strong columellar fold is not paralleled in any other Helix 

 except H. cepoides Lea. The surface-sculpture of unidentata is justlike 

 that of stu deriana. The uniform brown color is usually relieved by 

 an indistinct lighter peripheral girdle. The granulation of the em- 

 bryonic whorls is finer and less regular than in H. studeriana. We 

 are indebted to M. H. Dufo for many important observations 

 upon the mollusks of the Seychelles, made by him during a residence 

 there of four years. He says of this species : " It inhabits the mid- 

 dle region of the mountains, sometimes upon large trees, but usually 

 on bushes or climbing vines. During the pleasant season they hide 

 under the soil or in rock-crevices, and do not come out except in 

 winter or during rain storms of several days duration. They feed 

 upon green leaves. Movements slow." 



The figures on PL 61 as well as fig. 85 of pi. 5, vol. ii of the Man- 

 ual, were drawn from specimens in the collection of the Academy. 

 These figures and fig. 84, pi. 5, vol. ii of the Manual, show the 

 great mutation in form and degree of elevation of the species. The 

 H. militaris of Pfeiffer is merely an elevated specimen. 



H. STUDERIANA Ferussac. PL 61. figs. 18, 19, 20. ,- 



Shell large, depressed, imperforate ; spire low-conoidal and blunt ; 

 aperture very oblique, the columella nearly vertical, its inner edge 

 convex ; periphery not keeled. 



The shell is solid, of a compact, depressed form, not keeled at 

 periphery but encircled by an inconspicuous sulcus and usually a 

 line or thread there ; it is opaque, and either chestnut brown, becom- 

 ing olive-brown on the. spire and flesh-colored on the earlier two 

 whorls, smokey below just around the axis, or else of a clear light olive- 

 yellow tint, the spire darker. The surface is nearly lusterless ; the 

 earlier (embryonic) 3J whorls are cut by close oblique and spiral im- 

 pressed lines into a beautifully regular decussated pattern of squarish 

 granules ; the following whorls have rather blunt, rude wrinkles of 

 increment, and are covered by a close fine corrugation of irregular 

 wrinkles, obliquely descending in a direction at right-angles to the 

 growth-lines. Under a strong lens there is seen over this coarser 

 sculpture, an excessively minute, close decussation, like that pro- 

 duced by pressing a woven fabric upon plastic clay. The apex is 

 plane ; earlier whorls scarcely convex, with linear, superficial suture ; 



