32 Mr. Alder's Catalogue of Land and Fresh-water Shells. 



adjoining banks. As I have not yet succeeded in finding it alive, its title to a place 

 here may be considered as doubtful. 



Gen. BULIMUS. 



22. B. obscurus, Drap. 



Helix obscura, Mont. 

 Under stones in old quarries and woods ; most plentiful on a limestone soil. 



23. B. Itibricus, Drap. 



Helix lubrica, Mont. 

 In moss ; common. 



Gen. AZECA. 



24. A. tridens, Flem. 



Turbo tridens, Mont. 



On mossy banks in woods. Scotswood Dean and Meldon, Northumberland ; and 

 Causey Dean, near Tanfield, Durham. Very local, but generally found in abundance 

 where it does occur. 



The claim of this species to constitute the type of a distinct genus is disputed by some 

 conchologists who are very properly averse to the multiplication of genera on slight cha- 

 racters. A careful examination of this curious shell, however, which has never yet been 

 properly described, will prove that it cannot be included in any of the previously exist- 

 ing genera. It seems to form a link between Bulimus and clausilia, resembling the 

 former in shape and general appearance, but approaching more nearly to the latter, in 

 having the margin completely surrounding the aperture, and also more particularly in 

 having a longitudinal plate on the columella considerably within the aperture, similar in 

 situation, and making a slight approach in form, to the Clausium of the genus Clausilia, 

 though attached through its whole length and inflexible. If it be thought necessary to 

 change the trivial name of this species, on account of the smaller intermediate plaits, or 

 teeth, (which however terminate in the larger ones in the form of a y,) the specific 

 name of britannica proposed by Mr. Kenyon, seems preferable to the Matoni of Dr. 

 Leach. 



Gen. CLAUSILIA. 

 ^' C. bidens, Drap. 



Turbo laminatus, Mont. 

 Under stones in woods. 

 26. C. rugosa, Drap. 



Turbo nigricans, Turt. Brit. Fauna. 

 On stones, trees, &c., in woods ; frequent. 



A larger and rather more ventricose variety occurs in old limestone quarries near 

 West Boldon, and at Castle Eden, which has much the habit of a distinct species. The 



