Mr. Thompson on the Mollusca of b' eland. 93 



January, 1835, at the same time with Euplocamus plumosus. 

 They seemed partial to coming to the surface of the water in 

 which they were for some time kept, and to moving along with 

 the foot upwards. 



From the P. quadrilineata and P. cornuta (vol. 4. p. 29. 

 tab. 145. fig. 1 — 3.) of the f Zoologia Danica', the P. flava of 

 Montagu (Linn. Trans, vol. vii. p. 84. pi. 7-) and the P. li- 

 neatus of Risso, (Hist. Nat. l'Eur. Merid. iv. pi. 1. fig. 5.) 

 all the species of Polycera that I have seen described and 

 figured, the P. typica differs remarkably in the development 

 of the branchial lobes. The P. capensis, Freycinet, is known 

 to me by name only. 



All the Mollusca Nudibranchia treated of in this commu- 

 nication are for the first time recorded as Irish species. 



Mollusca Tunicata. 



The Mollusca Tunicata have in Ireland as in other coun- 

 tries engaged very little attention ; yet if mere outward beauty 

 be any attraction to the naturalist, where will he behold it 

 more surpassing than in the compound species of this portion 

 of the animal kingdom ? Of every hue — arrayed in purple 

 and gold — will he find them even in this " cold and cloudy 

 clime." 



The species of the British seas are now, I rejoice to state, 

 about to be investigated by naturalists highly qualified for 

 the task. This I learned when about to attempt entering on 

 the study of our native species; and communicating my spe- 

 cimens to the parties alluded to, that in connexion with their 

 own they might be properly elucidated, I at once ceased 

 from my incipient investigation. For this reason, the follow- 

 ing species, belonging to the first division, "Ascidies Simples/ 3 

 are placed, without regard to systematic arrangement, merely 

 under the name used by the author in whose work I found 

 them described. Small as is the number, the species are one- 

 half more numerous than those published in 1828 in Fleming's 

 British Animals. 



*Ascidia venosa, Mull. Zool. Dan. vol. i. p. 25. tab. 25. 



* This mark before the species denotes those which I have not seen re- 

 corded as British — the others are new only to the Irish Fauna. 



