Clare Island Survey — Acarinida. 39 47 



marine species Hyadesia fusca on the British coast is of interest, a number of 

 specimens were found amongst coralline sea-weeds in rock-pools on the 

 shore of Clare Island. Another interesting species is the ants' nest mite 

 Tyroglyphus Wasmanni, the hypopial nymph occurred in nests of the common 

 black ant, Formica fusca, at Mulranny, apparently the first definite record of 

 the species from Britain. 



The mites of the group Thrombidoidea, including such creatures as the 

 earth mites, spinning mites, &c, were but little collected, except for the 

 aquatic kinds. Indeed this part of the list is a record of casually collected 

 species often represented by single specimens. For the sea-mites of the 

 family Halacaridae I am mainly indebted to Mr. B. Southern who kindly 

 collected a number of these minute acarids during the scientific expeditions 

 of the Fisheries cruiser " Helga." Of the seventeen forms collected two 

 species and a variety are undescribed ; two of these were dredged in Clew Bay 

 in 24 f. on what has been described as " Bolygordius ground." This consists 

 of a bottom of gravel and shelly sand yielding a very interesting fauna of 

 polychaete worms and other creatures (see Parts 47 and 67). 



A special search was made on the coast of Mayo for examples of the 

 interesting littoral fauna recorded by Berlese, Trouessart and others from 

 the coasts of southern Europe. I am glad to record success in this respect ; 

 quite a number of these mites were found in their characteristic habitat 

 including a few new forms, the most interesting being Tliinozercon Michaeli 

 sp. nov. a peculiarly isolated acarid which must be regarded as the type 

 of a new family of the Gamasoidea, while the new genus Haluropoda is 

 represented by two species found commonly on the sea-shore and in salt 

 marshes. 



The more truly maritime forms are found well below high-tide mark 

 where they survive continual immersion by the sea. During the tides they 

 retire into minute crevices in the rocks, or under stones partly embedded in 

 sandy mud where small quantities of air are imprisoned; such species are — 

 Halolaelaps glabriuscidus, Gamasus Trouessarti, Cyrthydrolaelaps hirtus, Pacliy- 

 laelaps Uttoralis n. sp., Hydrogamasus Giardi (Dublin coast), Tliinozercon 

 Micliaeli n. sp., PhaidocyUiba Bcrlesii n. sp. (Dublin coast), Bdella decipiens, 

 Bdella capillala (or var.), Byncholophus rubripes, Rhagidia lialopliila and 

 Halotydeus hydrodromus var. albolineatus. Of the Pachylaelaps and Phaulo- 

 cylliba only single specimens were found, both are apparently undescribed 

 and in common with the other species mentioned they occurred under stones 

 well below high-water mark. 



There are also some species which live under stones and seaweed at or 

 about high-water mark yet they do not appear to relish the continuous 



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