Clare Island Survey — Acarinida. 39 99 



they are shorter with compactly clubbed extremities, in other specimens 

 these organs are more drawn out. In addition to the marginal hairs there 

 are five or six pairs of hairs on the dorsum of the animal. 



Distribution. — A widespread European species ranging into the Arctic 

 Circle (Franze- Joseph Archipelago, Spitzbergen, Michael). 



Oribata quadricornuta Michael. 



Evidently a local species in the district. Westport, on furze, July ; 

 Mulranny, under stones on the sea-shore in September. 



Distribution. — Finland; Germany; Holland; Algeria; Britain. 



Oribata ovalis C. L. Koch. • 



Abundant in moss. Clare Island, Achill, and Westport district. 

 Distribution. — Common and widely distributed in Europe. 



Oribata dorsalis (C. L. Koch). 



Mulranny, under stones on the sea -shore, and on the banks of stream 

 flowing from the Curraun lakes, September ; var. longiplumus Berlese, 

 common under bark in the Westport demesne, July. 



The specimens are referable to two recognizable forms. In one of these 

 the pseudostigmatic organs are shorter, closely resembling 0. alata var. 

 integer Berlese in this respect. I cannot say, however, that the specimens 

 are identical with this variety as they do not seem to agree in the other 

 characters mentioned by Berlese. The second form is a little larger, and 

 the pseudostigmatic organs are very long and strongly recurved, hair-like 

 and exceedingly finely setose at their extremities. This form is probably 

 the same as Berlese's 0. eliminatus var. longiplumus, which is described and 

 figured in the same paper (7, p. 30, pi. 1, rigs. 21, 22). In none of the Irish 

 specimens that I have seen are the pseudostigmatic organs sufficiently short 

 and clavate to enable one to refer them to typical 0. alata (Herm.) as this is 

 figured by Berlese (1, Fasc. lxxviii, N. 9) and other acarologists. 1 



Distribution. — This species has an extremely wide European range. 



1 Since these notes were written I have received from Dr. Berlese a paper dealing with the alata 

 group of the genus Oribata. (Acaii Nuovi, Manipulus ix, Redia, x, 1914.) A re -examination of 

 the Mayo specimens confirms me in the belief that the form with long recurved, pseudostigmatic 

 organs is 0. longiplumus, now established as a species by Berlese. The only difference is that the 

 transverse line dividing the cephalothorax from the abdomen is wanting in the Irish specimens, but 

 Berlese figures a variety (myrmophilus) of ihis species in which this line is evanescent. The form 

 with shorter and more clavate pseudostigmatic organs is not integer but 0. nervostis, Berl. recorded 

 from Norway, North America, and South Africa. Specimens of this form, found on the sea-shore at 

 Mulranny, measure about 653 /i in length by 486 /j. in breadth. 



