r 106 ] 



VI!. 



THE ACAEINA OF THE SEASHORE. 



By J. N. HALBEET, M.E.I.A. 



(Plates XXI-XXIII.) 



Read May 10. PuUUhcd Jdlt 28, 1920. 

 ISTEODUCTION. 



Thk object of this paper is to i-ecord a section of the work recently carried 

 out by Mr. R. Southern, of the Irish Fisheries Brancli, and myself on the 

 fauna of the intertidal area. This work was mainly ecological, an attempt 

 being made to study the associations of littoral forms, and for this reason it 

 was necessary to examine a large number of " stations " in the various zones 

 of the shore affected by the tides. 



Moanwhile, results of systematic iniport-aiice were oluaiiied in at least cue 

 group of animals, namely, the Acarina, or mites, wliich wiili the insects form 

 an interesting element of the intertidal fauna. It is necessary to describe a 

 numltcr of new fonns which have apparently escaped notice up to the present 

 time. For this reason it seems advisable to report (m these results, and so 

 make a preliminary use of the large iiiiinl.ii nf Held observations which are 

 now available. 



The localities select'ed for e.xamination are the rocky shore at Malahide 

 and the adjoining estuary on the Dublin coiust, and Ardfry, at the north- 

 eastern extit?mity of CJalway Bay, on the west coast of Ireland. At tlie first- 

 nieiitioiie«l place the work was greatly facilitated by the action of the Eoyal 

 Irish Academy in lending us the hut bequeathed to the Academy by the late 

 Mr. IL J. Usher, m.ili.a. 



The establishing of this hut on a suitable part of the shore at Malahide 

 enabled us to explore the intertidal area fairly thoroughly during favourable 

 tides, and without this help the work wouM have been much more difficult. 

 During a short visit in the early part of June, 191G. to the Marine Laboratory 

 maintained at Ardfry by the Fisheries Branch of the Department of Agri- 

 culture and Technical Instruction, investigations of the littoral fauna were 

 made on lines comparable to those in progress at Malahide. 



A short experience of this kind of shore-collecting soon convinced us that 

 gome form of sub-division of the int^.'rtidal area would be a great help towards 



