1906-1907.] Copepoda livmg as Messmates with Ascidiajis. 369 



which are widely apart and vary in size in different speci- 

 mens, are attached to the last thoracic segment : they extend 

 along each side of the abdomen, and reach to some distance 

 beyond its extremity. Each ovisac, which has its point of 

 attachment to the thoracic segment protected by the short 

 but broad fifth foot, contains a moderate number of fairly 

 large ova. The body is cylindrical in form, and distinctly 

 segmented. The thoracic limbs, as might be suspected from 

 the confined habitat, are very short, and the animal itself 

 appears to be sluggish. The ovisacs, which were of a red 

 colour, were easily noticed through the semi - transparent 

 integument of the digestive tube. Dr Canu says that he 

 found the male of E. fulgens is frequent in spring-time and 

 in September, while the female is common at all seasons 

 in the digestive canal of Polydinum luteum Giard.-*^ 



Genus Entekopsis Aurivillius. 



Very few species of Unteropsis have been described, and 

 none of them, as far as I know, has been recorded from 

 British waters, except that which I have described as 

 U. vararensis.^ They all seem to have a general resem- 

 blance to Enterocola, the female also being provided with two 

 external ovisacs as in that genus. All the species appear to 

 be moderately rare, and Dr Canu says that his Unteropsis 

 pilosus was described from a single female obtained in the 

 branchial sac of Diazona hehridica Forbes, one of the Social 

 Ascidians.^ Other two described species are E. diobius 

 Schimkevitsch and U. sphinx Aurivillius. 



Genus Aplostoma Canu. 



Four female examples of a species belonging to Canu's 

 genus Aplostoma were obtained in the alimentary canal of 

 a species of Ascidia, identified doubtfully as Ascidia (Ciona) 

 intestinalis. Only one specimen of the Copepoda was observed 



^ ' Les Copdpods du Boulonnais,' p. 217. 



^ 'Nineteenth Annual Keport Fishery Board for Scotland,' Pt. III., p. 241, 

 pi. xvii., figs. 28-34. 



^ ' Les Cop^podes du Boulonnais,' p. 220. 



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