1 906-1907.] Copepoda living as Messmates with Ascidians. 363 



but none of these have so far been recognised as members of 

 the British fauna. 



Genus Agnathaner Canu. 



Two species of Agnathaner have been recorded by Dr Canu 

 in his work already referred to, 1 but as only the males have 

 been described, the relative position of the genus is somewhat 

 uncertain. One of the species, Agnathaner typicus Canu, was 

 obtained in the branchial chamber of Styelopsis grossularia Van 

 Beneden, and the other, A. minutus Canu, in Gircinalium 

 concrescens A. Giard. Neither of the two species has been 

 observed in British waters. 



Genus Doropygus Thorell. 



The Copepoda of this and other allied genera differ dis- 

 tinctly in appearance and habits from Notodelphys, and consti- 

 tute the family Doropygidas. In this group the cephalothorax 

 is usually robust, and the posterio-dorsal sac with which the 

 females are furnished is in adult specimens large and crowded 

 with coloured ova : the colour varies to some extent, probably 

 owing to the advancing development of the embryos. Several 

 species of Doropygus have been described, and five at least 

 belong to the British fauna. They require careful examina- 

 tion, however, as the specific characters are somewhat obscure, 

 and are only reliable when dealing with mature specimens. 

 All the species are moderately large, but I have not met with 

 any British examples that reach the dimensions given by 

 Continental authors. Though these creatures have robust 

 bodies their legs are small, and, as might be expected, they 

 are rather sluggish in their movements. 



Doropygus pulex Thorell has been observed in large Ascid- 

 ians dredged at various places, as off the coasts of Durham 

 and Yorkshire, Shetland, Oban, and Loch Fyne. It has been 

 obtained off Millport in Ciona parallelogramma by Alexander 

 Gray, formerly of Millport Marine Station ; and Dr Canu also 

 gives the names of several species of Ascidians in which it has 



1 'Les Cop^podes du Boulonnais,' p. 210. 



