313 Mr. W. Thompson's Contributions to the Fauna of Ireland, 



Fuci at Skerries, Dublin coast. On its being submitted to the in- 

 spection of Mr. Alder, by whom the original specimen described by 

 Dr. Johnston was discovered in Berwick bay, he remarked, that the 

 species " appears to be pretty generally diffused, but nowhere com- 

 mon." He had obtained it last summer in Rothesay bay. 



f Doris Ulidiana, Thompson. 



On the 17th of February 1840, I procured three specimens of this 

 Doris among oysters brought to Belfast market from the neighbour- 

 ing coast of Down or Antrim, and after noting their general appear- 

 ance, colour, &c., set them apart as species unknown at least to the 

 British fauna. Mr. Alder having some time ago expressed a wish 

 to see my collection of Nudibranchiate Mollusca, it was placed in his 

 hands, and on this species coming under examination it was consi- 

 dered by him and Mr. Hancock to be new, and a description of it 

 drawn u]^ for their own use was kindly communicated to me. This 

 is as follows ; — within parentheses are my notes on the colour of the 

 li\'ing Doris. 



Doris Ulidiana. — " Length, from spirits, ^ inch, breadth ^ inch ; 

 ovate-oblong, rather straiglit at the sides, depressed [of a uniform 

 pale yellow, the intestines appearing through the skin of a dark co- 

 lour]. Cloak not extending much beyond the foot, rough with spi- 

 cula, and covered with large, unequal, obtuse tubercles, the spicula 

 collected in bundles in the tubercles and radiating at their base. 

 Tentacula [long and whitish], lamellated, without sheaths ; the 

 edges of the apertures plain. Branchiae consisting of eleven [beau- 

 tifully white] pinnated plumes, set in a semicircle round the anus. 

 Foot rather broad. Veil above the mouth semicircular." 



On being put in diluted spirits of wine, the tentacula were en- 

 tirely withdrawn, and the branchial processes lost their beauty by 

 discoloration, which changed them to the same hue as that of the 

 body. 



On comparing these specimens at the time they were procured 

 withthe most nearly allied species in my possession, the Doris mu- 

 ricata, Miiller (Zool. Dan.), they were noted down as being cer- 

 tainly distinct from it : — in being of a more elongate shape, in ha- 

 ving the tubercles differently formed, and, in proportion to the dimen- 

 sions of the body, their being not more tlian half the size of those of 

 D. muricata. Messrs. Alder and Hancock made the following com- 

 parative observations : " Comparing your D. muricata [a species they 

 had not seen before] with our D. uspera and your D. Ulidiana, we 

 come to the conclusion, so far as we can judge from specimens in 

 spirits, that these three are distinct, though nearly allied species. 

 D. Ulidiana differs from D. muricata in its much larger size, and 

 longer and more depressed form. The tubercles appear to be more 

 depressed, and the branchial plumes larger. From D. aspera it dif- 

 fers also in size and shape ; in having larger tubercles, the cloak 

 narrower, and the foot broader." 



