354 Messrs. Brady and Robertson on Dredging 



entirely, to some limited subject ; otherwise the novelty of the 

 creatures which he meets with, perhaps for the first time, will 

 be liable to withdraw his attention from any careful or minute 

 observation until his time is too far spent to allow of the se- 

 rious study of any particular group. We have ourselves often 

 erred in this way ; but last year (1868) we resolved to devote 

 our short furlough strictly to the examination of the Ento- 

 mostraca and smaller Crustacea of the district which we pro- 

 posed to visit. The following notes refer, therefore, almost 

 entirely to that class. We do not suppose that the lists here 

 given are by any means exhaustive : the restricted areas ap- 

 parently occupied by some species make it almost certain that 

 further opportunities of investigation would have revealed the 

 existence of others as interesting as those which were actually 

 observed* ; and there can be no doubt that both the marine 

 and freshwater loughs of Western Ireland, especially of the 

 Connemara district, offer yet a most promising, and in some 

 departments an almost untouched field of research to both 

 botanist and zoologist. 



Our dredging during this excursion was confined to the 

 coast in the neighbourhood of Westport, Clifden, and Round- 

 stone ; but we also found time to make a few gatherings in 

 the freshwater lakes of the district, and, en route^ to snatch an 

 hour or two of work in Dublin Bay. The terminus of the 

 Mullingar Canal at Dublin, from which we took some gather- 

 ings, afforded us a few interesting Ostracoda, amongst which 

 was one species {Gyiyridopsis ohesa) hitherto undescribed, 

 though known to us from one or two specimens taken in the 

 river Scheldt, as also from the occurrence of the valves in 

 some posttertiary lacustrine deposits. 



A most interesting feature in the fauna of the freshwater 

 lakes of the Connemara district is the intermixture of marine 

 or brackish-water species with those of strictly freslnvater 

 character. The small sheets of water to which we chiefly 

 refer lie scattered by scores or even hundreds over the plateau 

 bounded by the mountain of Urrisbeg on the south, the " twelve 

 pins" on the east, Clifden on the nortli, and the Atlantic on 

 the west. They are but slightly elevated above the present 

 sea-level ; and the presence in them of a partially marine fauna 

 would appear to indicate a perhaps not very far distant eleva- 

 tion of this tract of country. In several of these lakes occurred 



• Especially when we consider the small area from which the material 

 was taken ; the dredge purposely used took hold so quickly that it seldom 

 required to be drawn more than a few feet before it was full. The profu- 

 sion of life in the sea-bed is strikingly indicated by the fact of so many 

 members of one group being found within such narrow limits. 



