FERUSSACIA. 219 



Morocco. The most widely distributed forms are F. folliculus 

 and the very closely allied F. vescoi. Bourguignat is the chief 

 authority on this group ; and the well-known tendency of that 

 author to make species out of slight local races, or even from 

 extreme forms selected from a continuous series, has not 

 greatly helped an intricate subject. It is evident that the dis- 

 tinction between races and "species" is more or less arbitrary, 

 and a great many forms of various degrees of differentiation 

 exist. The sporadic distribution assigned to some of the 

 nominal species probably indicates that they are recurring 

 variations of wide-spread forms rather than independent 

 stocks. Morelet (Journ. de Conchyl. 1877, p. 248) believes 

 that F. folliculus and vescoi intergrade in characters, and are 

 not specifically separable. Wollaston has expressed the same 

 view; and with many specimens of half a dozen of the 

 nominal species before me, I find the alleged distinctions il- 

 lusive and difficult to apply in actual practice. Whether the 

 folliculus group consists of one or a dozen "species" must 

 be left an open question. 



The groups Folliculiana and Folliculina, have F. folliculus 

 as their type species. 



F. aphelina Bourguignat. "A Sicilian species having the 

 spire very long, analogous to F. vitrea of the island of Tene- 

 rife." (Ferussacia aphelina BGT., Revue et Mag. de Zool. 

 xvi, 1864, p. 207; Malac. de 1'Algerie p. 29.). No further 

 information has been published. It may possibly be what 

 Benoit described as Achatina nebrodensis. 



1. F. FOLLICULUS (Gronovius). PI. 41, figs. 53, 54. 



"Shell cylindric-elongate, smooth, glossy, subpellucid, cor- 

 neous-buff ; spire rather elongate conic, the apex rather obtuse 

 or a little acute. Whorls 6, slightly convex, irregularly in- 

 creasing, suture paler corneous margined; three first whorls 

 regularly increasing, the fourth a little larger, antepenulti- 

 mate whorl large, a little more rapidly descending ; last whorl 

 not half the total length. Aperture lunate-oblong; peristome 

 acute, simple ; columella short, straight ; outer margin excised 

 at the suture, then forwardly dilated; margins joined by a 



