Prof. A. Mousson on the Molluscan Fauna of the Canaries. 83 



smaller but seldom traversed eastward islands of Laiizarote and 

 Fuerta Ventura, — a disproportion scarcely owing to their natural 

 poverty, but probably only to our deficient knowledge. These 

 two latter islands, in every respect less cultivated, and, by their 

 easterly position, placed in close connexion, are those visited by 

 Herr Hartung. With other objects in view, he merely col- 

 lected what fell in his way ; yet even this scanty material pos- 

 sesses some interest, as conducing to the establishment of good 

 specific characters and authentic habitats. 



The following species had been recorded by M. D'Orbigny as 

 peculiar to Lanzarote and Fuerta Ventura : — 



Parmacella ambigua, Fer. 



Helix simulata, Fer. ; an oriental species, the name of which is 



probably improperly applied. 

 Helix monilifera, Webb. 



Lancer ottensis J Webb. 



sarcostoma, Fer. 



The following were added as common to all the Canaries : — 



Helix pisana, Miill., with its varieties. 



plicaria, Lam. From the former confusion of several 



different forms, its universal diffusion must be considered 



to want proof. 



ladea, Miill. According to Webb, rare on most of the 



islands. 

 Bulimus decollatuSy Brug. 

 Physa acuta, Drap. 

 fontinalis, Drap. Mr. Webb reckons both these species 



as of universal diffusion. 



Herr Hartung has brought back only the following species : — 



1. Helix pisana, Miill. The typical, more strongly perforated 

 form, which almost exclusively prevails from the shores of Egypt 

 to those of Spain, is very abundant in the Atlantic islands. 

 Amongst Hartung's specimens from the two islands are found 

 three forms which I introduce as varieties, although the last of 

 them, on account of its peculiar habit, would be considered by 

 many authors, perhaps rightly, as distinct. 



a. Var. clauso-inflata, MSS. Globose, inflated, thin, faintly 

 striated ; the perforation faintly marked by a slight elevation of 

 the unreflected pillar-lip ; white with indistinct lines ; sometimes 

 a very faint indication of a rounded keel above and beneath on 

 the last volution. The specimens are from Fuerta Ventura, but 

 it is also found in Teneriffe. 



b. Var. Alboranensis, Webb. Characterized by its small size, 

 globose shape, early-evanescent keel, thickening of the shell with 



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