22 The British Oceanic Entomostraca. 



character of the genus is found in the structure of the swim- 

 ming feet, the first four pairs of which are alike, each foot 

 consisting of two tri-articulated branches. The first antenna 

 of the male bears a remarkably large vesiculiform swelling, a 

 character not uncommon in this family, but nowhere better de- 

 veloped than in Tachiclius. The antenna is beset also with long 

 sete3 of very diverse form and structure, the uses of which, as 

 well as of the vesiculiform swelling, are very imperfectly, if at 

 all, understood. The antenna is represented at Fig. 1. 



Tisbe furcata, Baird. Ganthocamptus furcatus, Baird. Brit. 

 Ent., p. 210, plate xxv., figs. 1, 2 ; plate xxx., figs. 4 — 6. 



A species of very common occurrence in littoral situations, 

 and which has been described and figured elaborately by 

 Baird, Liljeborg, and Claus. A peculiar parasite of polypoid 

 form is noticed both by Baird and Claus as frequently infesting 

 this species. 



Westwoodia nobilis, Baird. Arpaciicus nobilis, Baird. Brit. 

 Ent., p. 214, plate xxviii., fig. 2, a — e. 



I do not know this species. Berwick Bay, Dover, and the 

 North Foreland are given as habitats by Dr. Baird. 



Dactylopus Steomii, Baird. Ganthocamptus Stromii, Baird. 

 Brit. Ent., p. 208, plate xxvii., figs. 3, 3a. 



This pretty little creature seems to be of somewhat rare 

 occurrence. I have taken it in rock pools on the Durham 

 coast, and on the Isle of Man, but have seen no examples 

 of it from other places. The localities given by Dr. Baird 

 are all on the east coast, ranging from Berwickshire to Dover. 



Dactylopus tisboides, Claus. Claus^ Diefrei lebenden Cope- 

 poden, p. 127, t. xvi., figs. 24 — 28. 



A species which I had been accustomed to refer to Sarpac- 

 ticus chelifer, I have now little hesitation in recording as D. 

 tisboides, Claus ; though I am unable to state with certainty 

 to which of the two species the figures and descriptions of 

 Dr. Baird and Liljeborg refer. Probably they were taken 

 indiscriminately from both species. Be this as it may, the 

 form which I refer to D. tisboides is, so far as my observations 

 extend, by far the more common of the two. I have taken 

 it abundantly on the coasts of Northumberland and Durham, 

 and in the Isle of Man, and it forms the bulk of one of Mr. 

 Norruan's Shetland gatherings. The characters by which it 

 may most easily be distinguished from Harpacticus chelifer are 

 (1) the form of the male antenna, which exhibits a large 

 vesicular swelling similar to that of Tachidius brevicornis; (2), 

 the first foot, which, besides minor differences, has, about the 

 middle of the small inner branch, a long plumose bristle reach- 

 ing nearly to the extremity of the ramus ; and (3) the shape 

 of the lower foot-jaw, which is a simple, somewhat oval, clawed 



