TRTCHONISCOIDES SARSI 35 



TRICHONISCOIDES SARSI, A WOODLOUSE NEW 

 TO THE SCOTTISH FAUNA, ON THE ISLE 

 OF MAY. 



By William Evans, F.R.S.E. 



While spending a few days on the Isle of May during the 

 second half of September 1910 I found, under stones on the 

 margin of a grass field south of the lighthouse buildings, a 

 number of small woodlice belonging to the family Tricho- 

 niscidae. The majority were the common Trichoniscus 

 pusillus, but there were two specimens of a different, and to 

 me unknown, species. These I sent to Mr R. S. Bagnall.who 

 recognised them as belonging to the genus Trichoniscoides, 

 G. O. Sars ; but owing to their imperfect condition he could 

 not say to which species. On 7th November 19 12 I devoted 

 half an hour to turning over stones in the same locality, and 

 secured, besides several of Trichoniscus pusillus, an example 

 of T. pygmceus, G. O. Sars, and one of the Trichoniscoidcs. 

 These have been recently submitted to Dr W. E. Collinge, 

 who is preparing an exhaustive monograph of the British 

 Terrestrial Isopoda, and he unhesitatingly identifies the 

 Trichoniscoides as T. sarsi, Patience. In all particulars, he 

 says, it agrees with the original description, except in colour 

 a point of little importance, in view of the length of time the 

 specimen has been immersed in spirit. 



Trichoniscoides sarsi was separated from T. albidus 

 (Budde-Lund) by Mr Alex. Patience in a paper, published in 

 1908, in the Annals and Magazine of Natural History (ser. 8, 

 vol. ii., pp. 84-88, pi. vi.), his specimens of the former being 

 from Norway whence Prof. Sars had recorded and described 

 it under the name of T. albidus (B.-L.) and those of the latter 

 from the west of Scotland (Clyde area). At that time 

 T. sarsi was not known to occur in the British Islands; but a 

 few years later, namely in March 191 2, Mr Bagnall discovered 

 it on the coast of Yorkshire, as recorded in The Zoologist for 

 May of that year, p. 193, and he has since then (in July 1914) 

 taken it on the Durham coast (see The Vasculuvi for June 



