NUDIBRANCHIATA. 273 



among oysters brought to Belfast market from the neighbouring coast of 

 Down or Anti'im, and after noting their general appearance, 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 considered by him and Mr. Hancock 

 to be new, and a description of it drawn up for their own use was kindly 

 communicated to me. This is as follows ; — within parentheses are my 

 notes on the colour of the living Don's. 



Dorin UlidicDia. — " Length, from spirits, ^ inch, breadth \ inch ; 

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

 yellow, the intestines appearing through the skin of a dark colour]. 

 Cloak not extending much beyond the foot, rough with spicula, 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 a2)ertures plain. 

 Branchijfi consisting of eleven [beautifully 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 entirely 

 withdrawn, and the branchial processes lost their beauty by discoloration, 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 with the 

 most nearly allied species in my possession, the Doris mnricata, Miiller 

 (Zool. Dan.), they were noted down as being certainly distinct from it : — in 

 being of a more elongate shape, in having the tubercles differently formed, 

 and, in proportion to the dimensions of the body, their being not more 

 than half the size of those of D. mnricata. Messrs. Alder and Hancock 

 made the following comparative observations : " Comparing your D. 

 muricata [a species they had not seen before] with our D. aspera and 

 your D. U/idiana,yve come to the conclusion, so far as we can judge from 

 specimens in spirits, that these three are distinct, though nearly allied, 

 species. D. U/idiaita differs from D. tnnricata 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 differs 

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

 and the foot broader." 



D. ohvelata, Johnston. 



Mr. Hyndman procured a specimen of this Doris on Fuci at Skerries, 

 Dublin coast. On its being submitted to the inspection 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 ge- 

 nerally diffused, but nowhere common." He had obtained it last summer 

 in llothesay Bay. 



Doris muricata, Mull. 

 I have not unfi'equently taken this minute species Avhen dredging (accom- 

 panied by Mr. Hyndman) in the louglis of Strangford and Belfast ; it was 

 generally adhering to the leaves of tangle {Latuiiiaria (/ii/ifnta). MuUcr 

 describes it as 5 lines long by o broad : my specimens were all even under 

 this size. The D. muricata has hitherto been unnoticed in the British seas. 



D. aspera, Aid. and Hanc. 

 Very young examples of a Doris, and most probably (according to Mr. 



