126 BRITISH COPEPODA. 



slightly produced and armed with three spine-like 

 setse ; second joint triangular, beset with five or six 

 seta3 on the outer, and one near the apex of the inner 

 margin. First two joints of the abdomen (fig. 9) very 

 wide and fringed with small cilia ; the second joint 

 produced downwards into two broad triangular pro- 

 cesses (b b), third joint forming two similar but smaller 

 projections (c c) ; all the abdominal joints, as well as 

 the caudal segments, very short and broad. Length 

 ^th of an inch (1 mm.). Colour yellowish, more or 

 less banded with deep crimson, the parts of the body 

 which exhibit the colouring being usually the second 

 and third thoracic segments and two or three of the 

 median joints of the upper antenna, but the bases of 

 the limbs, tail, &c., are liable to partake in the red 

 colouring. 



This is a widely distributed species, and sometimes 

 occurs in considerable abundance ; it is readily dis- 

 tinguished from all other species of Thalestris by the 

 aculeate character of the spines of the swimming-feet. 

 It has occurred sparingly in dredgings from the coast 

 of Durham and Yorkshire off Marsden, ten fathoms, 

 Hawthorn, twenty-seven fathoms, and Red Cliff, thirty- 

 five fathoms ; Scilly Islands, ten to twelve fathoms, 

 and also on alga3 in Porcressa Bay, St. Mary's; 

 dredged off Cumbrae and Portincross, Firth of Clyde ; 

 Port Dinlleyn, North Wales ; Clew Bay and Lough 

 Swilly, Ireland ; plentiful on fronds of algae in Mulroy, 

 Clifden, Birtirbuy and Ventry Bays ; Oban (Rev. A. 

 M. Norman). 



