loS The Irish Nainralist. June, 



ON THE IRISH SPECIES OF OBISIUM ; 



^VITH SPKCIAI. REFERENCE TO ONE FROM CxLENGARIFF 

 NEW TO THE BRITANNIC FAUNA. 



BY H. WATXIS KEW. 



Obishnn imiscorum, Leach, is well known in Ireland (1-5) 

 and two other species have recentl}^ been discovered : 

 Obisium ^naritiinum, Leach, on the shores of the Ba3'S of 

 Kenmare and Bantr}' (5) ; and another species — the one with 

 which we are more especialh' concerned — on a rock}' wooded 

 hillside at GlengarifF. 



Leach's types of O. imiscorum nnd O. maritiimmi, the former 

 Scottish and the latter English, are preserved in the British 

 Museum, where they have been examined by Cambridge (4) 

 and by the writer ; and thus, with these species, no difficulties 

 of identification arise. The remaining species, how-ever, is in 

 different case ; for it is unknown in Britain — and thus new to 

 the Britannic fauna — and the task of determining it w^as beset 

 with serious difficulties. 



The genus has many species in Europe ; and i^;, moreover, 

 badly in want of thorough revision. We have a good account 

 of one species by Hansen, and able re-descriptions of several 

 b}^ Ellin gsen, but for the rest w^e have to rel}^ almost entirely 

 on L. Koch (6) and Simon (7), the former without figures and 

 the latter insufficiently illustrated — and both published at a 

 time when the extent of the genus and the critical character 

 of it had not become apparent. It does not seem to have been 

 realised at that time that the species were liable to differences 

 of sex, to individual variation, and to differentiation into 

 geographical races; moreover, the characters relied on, 

 e.g. the development of the hand and relative length 

 of hand and fingers, are now known to be unstable ; and 

 other features which have been found to be of value, 

 such as the character of the teeth of the fingers, are not 

 mentioned at all. In these circumstances, the Glengariff 

 specimens could not be identified from the literature; but the 

 WTiter was fortunately permitted to submit them to Mr. 

 Ellingsen and afterwards to M. Simon ; and was at length 

 favoured by the latter distinguished arachnologist with 

 certain specimens from his collection for comparison, 



