Dr. T. Scott on British Copepoda. 464 



with those previously noticed in the female, render the 

 removal of this species from the genus Cylindropsyllus 

 necessary, and the new genus I propose for its reception is 

 named D' Arcythompsonia in compliment to Professor D'Arcy 

 Wentworth Thompson, C.B.,of University College, Dundee. 



Genus Harrietella *, T. Scott, nov. 

 (PL XI. figs. 9, 10.) 



An apparently new species of Copepod is described in 

 part iii. of the ' Twelfth Annual Report of the Fishery Board 

 for Scotland.' This Copepod was provisionally ascribed to 

 the genus Laophonte, Philippi, with which it partly agrees. 

 It was mentioned, however, in some general remarks on the 

 species that there were certain important differences that 

 could hardly be reconciled with the definition of that genus ; 

 but as only one or two specimens had been obtained, I pre- 

 ferred to leave it in that genus till additional examples should 

 be procured. The first specimens were obtained within the 

 valves of a dead Lamellibranch (Cyprina) shell dredged in 

 the Firth of Forth, but others were afterwards found in 

 considerable numbers in the Firth of Clyde in the crevices of 

 partly decayed wood brought up in the trawl-net, and it is in 

 pieces of submerged and partly decayed wood I now most 

 frequently find the species. An examination of these 

 additional specimens showed that the differences referred to 

 were not accidental, but characteristic of the species, and that 

 the species could not be retained in the genus Laophonte. I 

 now therefore propose to remove it from that genus to the 

 one described below. 



Description of the genus Harrietella. — Female. Body tole- 

 rably robust, cephalothorax depressed, greatest width fully 

 half the entire length of the animal ; abdomen narrow. An- 

 terior antennae short, six-jointed. Posterior antennae short, 

 two-jointed ; outer ramus small and uniarticulate. Mandibles 

 small and narrow, apex truncated and provided with a few 

 small teeth. The other mouth-organs similar to those in 

 Laophonte. The first three pairs of thoracic legs, which are 

 tolerably robust, have the inner branches two- and the outer 

 three-jointed. In the first pair the inner branch is elongated, 

 the first joint being considerably longer than the entire outer 

 branch ; the second is short and armed with a stout terminal 

 claw, as in Laophonte. In the second and third pairs the 



* This genus is named in compliment to Miss Harriet Richardson, 

 author of 'A Monograph on the Isopods of North America.' 



