rg2 JOURNAL OF CONCHOLOGV. 



ARION OCCIDENTALTS: 



AN APPARENTLY NEW SPECIES. 



By T. D. a. COCKERELL, F.Z.S. 



(Read before the Conchological Societj', Dec. 7, 1892). 



In October, 1890, the Rev. J. W. Horsley kindly gave me a 

 living Avion, which he had found at Jurancon, near Pan, Basses 

 Pyrenees, under stones. Ever since, I have had the description 

 by me, hesitating to propose a new species of French Arion ; 

 but as I am still unable to satisfactorily place the slug with any- 

 thing described, I venture at last to submit an account of it. 



Arion occidentalis n. sp. 

 Length about 25 mill, mantle about 11 mill. long. Respiratory 

 orifice not very much anterior Tentacles small, black. 

 Head black. Mantle wrinkled in contraction. Rug^ of 

 body ill-defined, not very numerous, large, elongate. Neck 

 black, with four impressed lines, joined by more obscure 

 transverse ones. Tentacles granulose. Mantle subrugose, 

 much thrown into folds. Ground colour of body and 

 mantle pale reddish-ochre, browner on back. Back of 

 mantle and body with numerous small black spots. Sub- 

 dorsal area pale, and then black lateral bands, strong and 

 broad on body, less developed on mantle, going over, not 

 enclosing, the respiratory orifice. Sides of mantle peppered 

 with black. Body below lateral bands gradually becoming 

 grey. Edge of foot pale ochre, with some minute grey 

 specks, but no transverse lineoles. Sole yellowish, median 

 area slightly greyish. Slime whitish or very pale yellow, 

 not opaque ; that exuding from the caudal pore is appa- 

 rently yellow. (Description from a living specimen). 

 Genitalia somewhat peculiar. The patronenstrecke is moder- 

 ately stout, and strongly curved at its end, the curved 

 portion gradually tapering into the vas deferens. The 

 spermatheca is oval, of fair size, with a duct about as long 

 as itself A long muscle arises close to the proximal end 

 of the duct, but not from it. The lower portion of the 

 oviduct is distinctly swollen, the swelling being fusiform in 

 shape. There is a distinct upper vestibule, which is larger 

 than the lower. The hermaphrodite gland is dark and 

 imbedded in the Uver, its duct is yellowish white, and its 

 proximal half is repeatedly curved. The spermatheca is 

 pinkish. 



J.C, vii., Apr. 1893. 



