154 



The Irish Naturalist. [June, 



The sponge Hymeniacidon celata, Bowk. {Cliona celata, Grant), 

 occurred perforating the hard Carboniferous limestone near 

 the Fairy Bridge at the eastern end of Donegal Bay. 



The patches at the surface exhibited a very characteristic 

 appearance, and upon vSplitting the rock it was found to be 

 closely perforated by the sponge for a depth of two or three 

 inches. A well-known boring sponge, Clio?ia is commonly 

 found inhabiting oyster and other shells all round the 

 coast, but only occasionally is it met with in limestone. 

 Bowerbank records it thus only from the limestone rocks 

 around Tenby. 



Among the Crustacea, a single specimen of the small Isopod, 

 Dy7iamene Montagui, Leach, was obtained by Prof. Johnson 

 from amongst the sea- weeds. It has previously been recorded 

 from Ban try Bay. 



Many specimens of the Sea-Hare, Aplysia punctata, Cuvier, 

 were met with in the shallow rock-pools west of Bundoran, 

 and also near Aughrus Point. Most were in the act of laying 

 their strings of brown-pink spawn. The majority were of a 

 uniformly dark olive green colour, while others were sprinkled 

 with small opaque v/hite patches over various parts of the 

 body. Mr. Garstang has shown {Jour^i. Mar. Biol. Assoc, (n.s.) 

 vol. i.. No. 4, 1890, p. 403) that this species changes with 

 growth from a violet, purplish, or rose-red colour, through 

 brownish-red and brown to olive-brown or Olive-green. The 

 rock-surface of the pools in which the present specimens were 

 found was coated with the pink Lithothamnio7i polymorphuvi to 

 which the dark Aplysice offered a great contrast. 



Prof. Johnson found the rare Nudibranch, Hermcea bifida^ 

 Montagu, while examining the weeds collected at low-water. 

 It was living upon Haluriis ( Griffithsia) cquisdefolius, to which 

 the lake-red colour in its dorsal papillae presented a remarkable 

 resemblance. This protective or warning resemblance to the 

 objects upon which Nudibranchs live has lately been the sub- 

 ject of various papers by Prof Herdman, Mr. Garstang, and 

 others. Hcrjticea bifida has been the object of some of Mr. 

 Garstang's experiments at Plymouth {[ourn. Mar. Biol. Assoc, 

 (n.s.), vol. i.. No. 2, Oct., 1889, p. 173) where it is interesting 

 to find that the creature, which there was also collected by 

 Prof. Johnson, lives upon the same Alga as at Bundoran. It is 

 shown that its colour is purely adventitious, being determined 

 mainly by that of the food within it undergoing digestion. 



