ON THE SPECIFIC IDENTITY OF THE OmSCUS FOSSOA' 143 



ON THE SPECIFIC IDENTITY OF THE WOOD- 

 LOUSE, ONISCUS FOSSOR, KOCH. 



By Walter E. Collinge, M.Sc, F.L.S , Research Fellow of the 



University of St Andrews. 



The terrestrial Isopod termed Oniscus fossor was described 

 by Koch^ in 1838, and with a few exceptions has been re- 

 garded by the majority of workers as a synonym of O. asclhis, 

 Linn. ; but in the light of our more recent knowledge of the 

 terrestrial Isopoda it seems worth while re-examining the 

 subject. 



Kinahan," in 1857, firsi! recorded O. fossor as a British 

 species from Dublin, Epping Forest, and Chisselhurst, 

 stating that the body is "oval, covered with numerous 

 rough granulations, which give it a powdered appearance ; 

 head convex ; lateral lobes moderate, rounded ; frontal line 

 produced into a triangular lobe which belongs to the head, 

 not to antennal ring." Whole animal much smaller than 

 O. asellus. 



G. O. Sars''^ remarks, "The Oniscus fossor of Koch is 

 scarcely different from this species [^Onisais asellus\ the 

 characters assigned to this form being such as pretty well 

 apply to younger specimens of Oniscus asellus^ which are 

 generally of a duller appearance, with the dorsal face more 

 roughly granulated than in adult animals." 



Budde-Lund* gives it as a doubtful species. 



Scharff ^ states that he " submitted specimens of Prof. 

 Kinahan's Oniscus fossor to Prof. Budde-Lund, who failed to 

 recognise any specific distinction between it and O. asellus^ 



In April 191 3, Mr P. A. Aubin very kindly forwarded to 

 me a number of small Oniscoids from St Helier, Jersey, 

 which agreed in every particular with Kinahan's description. 

 Similar specimens have been received from Miss M. Grace 

 Giles (February, 1914) from Bonchurch, Isle of Wight; 



1 Deutschland Crtist., 1838, Heft 22, pi. xxii. 

 - Nat. Hist. Rev., 1857, vol. iv., p. 21 (reprint). 

 3 Crustacea of Norway, 1898, vol. ii., p. 172. 

 •* Crust, hop. Terr., 1885, p. 205. 

 5 Irish Ndt., 1894, vol. iii., p. 28. 



