2 The Irish Nahiralist. 



from Donegal Ba\' to Queenstown Harbour. It occurs 

 nowhere else in the British Isles, but turns up again in the 

 Channel Islands. It is capable of boring holes, probably by 

 means of its teeth, in the soft limestone to a depth of one-half 

 or more of its own height; where, however, the rocks, as at 

 Dog's Bay in Connemara, consist of the harder granite, the 

 urchin is incapable ofboringinto them, and simply rests upon 

 the bottom of the pools. Many of them are partially covered 

 by empty shells, such as those oi Patella, P2irpura, 2.r\6iLitto7ina. 

 Considering the spin}^ nature of their skeleton it is very diffi- 

 cult to conceive that this feature can be in any way concerned 

 with protection to the individual. Again, they are almost 

 invariably associated in the pools with luxurious growths of 

 the light pink encrusting Lithothain7iion polymorphtwi, to 

 which they offer the strongest contrast, almost suggestive of a 

 warning combination. 



In some of the shallow pools, some distance above low- 

 water mark, we found numbers of the sea-slug Aplysia ptmctata, 

 Cuv., their dark olive-green colour also contrasting strongly 

 w^ith the light Lithothamnion. A few minutes sufficed to 

 obtain two or three dozen, many of them in the act of laying 

 their strings of brown-pink spawn. 



On this part of the shore, and still more so on the rocks and 

 cliffs north of Bundoran, are to be found more or less firm 

 masses of sand and fragments of shells built into tubes by the 

 worm Sabellaria alveolata, Linn., and almost resembling a 

 honey-comb in appearance. These masses, no doubt, exer- 

 cise a preservative geological influence on the rocks, the 

 hollows and irregularities about forming also a protection for 

 various forms of life. 



In one of the caves with a smooth floor covered by water, 

 and with stalactitic and stalagmitic masses further in, we 

 came across quite a crowd of small hermit-crabs, Fagunis, 

 and very interCvSting it ^ was to watch their little battles over 

 the bodies of some of their unfortunate companions who had 

 been torn from their protective gastropod shell. Here also I 

 met with a few specimens oi Anemonia siUcata {Anthea cereus), 

 Penn., of the variety with iridescent green tentacles tipped with 

 red. This species, not so abundant in Donegal Bay, I have 

 met with in great numbers in Roundstone Bay, giving to the 

 h^^s oi Zostera there quite a flower}^ appearance. Actinia 



