100 DUBLIN NATTJEAL HISTORY SOCIETY. 



be the primary object of all natural history investigations, viz. the affix- 

 ing the proper limits of distribution to each species. 



The bays more particularly examined were two in number, Liscan- 

 nor and Ballyvaughan ; and both, I regret to say, were examined under 

 peculiar disadvantages, owing to the state of the wind and the weather. 

 It is of great importance in all investigations of this kind that the na- 

 ture of the localities examined should be stated, as the shore characters, 

 in a great measure, limit the animals found both as to numbers and va- 

 riety. 



Liscannor Bay differs in the physical characters on its two sides, but 

 I found little difference as to the species. It may be generally described 

 as flat, slaty slabs of rock, with but few large rock-pools, and those ge- 

 nerally shallow. Low, overhanging ledges, however, supply the place 

 of these. Part of the shore is shingly, and part sandy. These are ge- 

 nerally unproductive. Numbers of loose, large stones lie in parts on the 

 ledges of the rocks, and these I found tolerably productive, especially 

 of Holothuriadae. 



Ballyvaughan Bay, or at least the part near the village, is very cha- 

 racteristic. A light silty mud covered nearly every part of the rugged 

 shore, the only place one had a chance of findiag anything being under 

 the overhanging ledges, and in the perforations, which in many places 

 regularly riddle the rocks. These perforations manifestly (at least the 

 larger and more productive) the boring of Pholas, Tapes, and Yene- 

 rupis, furnish some interesting animals, particularly among the worm- 

 like echinoderms, some of which I have not yet identified to my satis- 

 faction. 



The chief object of my researches was the Crustacea, and therefore 

 I will first treat of these, taking the most characteristic species, and then 

 making a few comparisons between the other species met and the same 

 species as they occur ia Dublin and elsewhere. 



'^ Facile princeps,^^ as characteristic of the west coast, must be consi- 

 dered the florid crabs, XantJio florida and Rivulosa. The first of these 

 occurs under nearly every stone, about half-way down the littoral zone, 

 completely replacing, or nearly so, the common green crab (C. mcenas) 

 of the eastern shores. They vary much in colour and size, the younger 

 specimens being often beautifully painted ; generally speaking, the tips 

 of the claws are black ; but the variety with light-brown claws is by 

 no means uncommon. I find in all adult specimens that the fingers 

 have at least one distinct groove, and sometimes two; it is, neverthe- 

 less, easily known from the next by the absence of dense hairs on the 

 5th, 6th, and 7th points of the posterior legs. I did not find the species 

 in ova. Its general colour is dark red, almost as deep as the colour of a 

 black cherry. 



Xantho rivulosa. — Of this species very little appears to have been 

 known as regards either its distribution or habits, as an Irish species, 

 until noticed by me at Yalentia, although the species as Irish had been 

 recorded by Captain (now Colonel) Portlock, nearly twenty years pre- 

 viously. It has been now established as frequenting the entire of the 



