128 BRITISH COPEPODA. 



margin of the segments finely ciliated. The ovarian 

 sac forms a conspicuous prominence on the back of 

 the animal, and has its angles well rounded. The 

 ovaria, according to Thorell, are greenish yellow, the 

 ova brown green. Length* of female -^th ^th of an 

 inch, of male -^jih j^th of an inch (3 5 and 1| 2 

 mm.). 



Mr. Norman has recorded this species as occurring 

 in the " branchial sac and water-passages of Ascidia 

 venosa " from Shetland. I have not myself seen any 

 British specimens, and my drawings have been made 

 entirely from Swedish specimens, for which I am 

 indebted to the kindness of M. Thorell. The follow- 

 ing list of localities is given by Dr. Baird (loc. cit.), but 

 it must be remembered that at the date of his work 

 the Ascidian parasites were scarcely at all known, and 

 it is extremely probable that many of the specimens 

 then named N. ascidicola might now be referred to 

 other species of the genus. " Belfast Bay ; Strang- 

 ford Lough, County Down ; W. Thompson and G. C. 

 Hyndman, Esqrs., Killery Bay, County Galway; R. 

 Ball and W. Thompson, Esqrs., Bangor, County 

 Down; R. Peterson, Esq., Glandore Harbour, County 

 Cork, Dublin Bay, and Southampton Water ; George 

 J. Allman, Esq. In the branchial sac of the Ascidia 



communis." 



The characters upon which M. Thorell has founded 

 the seven species of Notodelphys described in his 

 work are mainly the length and proportions of the 



* The lengths of the species of Notodelphys, except N. prasina, are 

 those given by M. Thorell. 



