22 22 Proceedings of the Royal Irish Academy, 



specimens were found living on two medium-sized plants of Codiuni taken 

 from rock-pools at low tide, Portarriv, and plants from Portkilly, Portlea, 

 and other stations were hardly less productive. The largest specimen 

 taken measured 6 mm. in length. 



The species spawned freely in the laboratory on the island two days 

 after capture, and many of the spawn-clusters were much more convoluted 

 than those shown in Alder and Hancock's plate (" Monog. Brit. Nudibr. 

 Moll '), fully 6 coils being counted in one cluster. 

 Elysia viridis Montagu. W. Almost as abundant on the island as the 

 preceding species and occurring about low-water mark in the same stations 

 on the S. and E. shores. Occasionally found on Cystoseira ericoides, but 

 much more frequently and abundantly on Codium tomentosum , with 

 the colour of which it assimilates almost as closely as does Hermaea 

 dendritica. The largest specimen taken was 1 inch long. 

 The brown variety olivacca occurred near Carrignapartan. 

 Limapontia capitata Miiller. TV. E. Pare ? In stagnant rock-pools near 

 high-water mark, always on the green seaweed Cladophora sericea 

 Kiitz. In two stations on Clare Island, at Portarriv in July, 1909, and 

 at Portkilly in August, 1910, one specimen in the first station and 12 in 

 the second. Also taken in a similar station at Old Head on the main- 

 land in July, 1909, when 25 specimens were picked out of one small tuft 

 of Cladophora. The Old Head specimens were but 1 millimetre in 

 length : those taken at Portkilly were almost 3 millimetres. 

 Actaeonia Cocksii Aid. and Hanc. ( Cenia Cocksii Aid. and Hanc. ). TV. Pare : 

 Four specimens were taken along with Limapontia on Cladophora sericea 

 in rock-pools at Portarriv, Clare Island, July 20, 1910. On a first 

 examination in the laboratory on the island the head showed the short, 

 blunt appendages relied on by Alder and Hancock (Ann. & Mag. Nat. 

 Hist., 2nd Ser., i, p. 403) as the chief distinctive character of their 

 Actaeonia corrugata, and the specimens were accordingly so named. 

 Two months later, however, I became convinced that they were really 

 referable to Actaeonia Cocksii, first described, named, and figured as 

 Cenia Cocksii by Alder and Hancock (loc. cit., p. 104, Plates XIX 

 and XX). 



Two of the four specimens taken at Portarriv lived with me, feeding 

 on Cladophora, up to the 3rd November, or for fully two months and a 

 half, and during this period the head-appendages developed into distinct 

 tentacles one-seventh the length of the animal, i.e. 0'5 mm. to a body- 

 length of 3-5 mm. The animals agreed in all points with the detailed 

 description of Cenia Cocksii given by Sir Charles Eliot in his Supple- 



