Clare Island Survey. 



43 

 MARINE ISOPODA AND TANAIDACEA. 



BY W. M. TATTEESALL, D.Sc. 



Read April 22. Published June 4, 1912. 



The area covered by the present report is the same as that given by me in 

 the report on the Cumacea and Schizopoda, namely, from Blacksod Bay in 

 the north to Slyne Head in the south, and seaward to the 50-fathom line. 

 I have already published a paper on the Isopoda of Ballynakill and Bofin 

 Harbours, 1 and I have incorporated the records from that paper in the present 

 report, which is, therefore, a complete list of the species of marine Isopoda 

 known to occur in the Clare Island district. 



One species, Tanais cavolinii, is now recorded from Ireland for tbe first 

 time, while the specimens of Pseudione sp. from Porcellana longicomis appear 

 to be the first Bopyrids found on this crab in British waters. One species, 

 Paratanais batei, is new to the district. In the paper mentioned above I 

 have given tables indicating the known geographical distribution of the 

 British and Irish Isopoda. It will, therefore, be sufficient here to mention 

 that out of the thirty-six species of shallow- water Isopoda known to occur in 

 the Clare Island marine area, twenty-two extend to Norway and eighteen to 

 the Mediterranean, while only nine species are common to all three districts. 

 Eight of the species are known from the coasts of North America. This 

 result is very similar to that noted for the Cumacea and Schizopoda, namely, 

 that the shallow-water marine fauna of the west of Ireland is a blending of 

 boreal and Mediterranean species, in very nearly equal proportions. 



Only four of the species noted below extend into deep water, namely, 

 Gnathia oxyuraea, Girolana borealis, Janira maculosa, and Munna kroyeri, 

 while Eurydice truncata and Idotea metallica are pelagic species which extend 

 occasionally far out to sea. In fact, I. metallica is a true oceanic species, 

 usually associated with floating barnacles and timber, and only reaching 

 littoral waters under stress of weather. 



1 Fisheries, Ireland, Sei. Invest., 1904, n. (1905). 



K.I.A. PKOC, VOL. XXXI, A $3 



