of the, Fishery Board for Scotland. 255 



small and apparently two-jointed secondary branch, which is articulated to 

 the inner edge of the basal joint; the basal joint is furnished with three 

 strong terminal setae of moderate length, plumose on the distal half ; the 

 secondary branch is armed with a few small terminal spines (PI. XVII., 

 %. 37). 



The first maxillipedes are small and apparently composed of two joints, 

 of which the end-joints are the smallest, each maxillipede is armed with 

 two moderately strong terminal claw-like spines, and as they are slightly 

 curved inwards, they form, with the end-joint, a moderately powerful hook 

 (PI. XVII., fig. 38). 



The second maxillipedes, which are larger than the first pair, are each 

 composed of five joints, the first and second joints are of moderate size but 

 the three end ones are small, the terminal claw-like spine is longer than 

 the entire length of the three end joints (PI. XVIII., fig. 23). 



The thoracic feet. — The first four pairs of thoracic feet are all somewhat 

 similar, they are each composed of a stout two-jointed basal part, which 

 bears two sub-equal three-jointed branches at its distal end; the outer 

 branches are armed on the exterior margin with several small, slender 

 spines, while the inner margins of both branches are furnished with 

 plumose setas (PI. XVIIL, figs. 24 and 25). The fifth pair consist each of 

 a single uniarticulated lamelliform branch, about three times longer than 

 broad ; each branch is provided with six small plumose setas — one near 

 the middle of the inner margin and five arranged round the apex (PL 

 XVIII., fig. 26). 



The ovisacs are very large and contain numerous ova. No males have 

 yet been observed. 



Habitat. — On the gills of a scarcely full-grown Lobster, captured by 

 Mr. H. C. Williamson in Bay of Mgg, near Aberdeen, June 30th, 1900. 



Remarks. — Though Nicothoe astaci appears to be moderately frequent 

 on the gills of Lobsters captured on various parts of the English coast, I 

 do not know of any previous authentic record of its occurrence in Scottish 

 waters ; Edward of Banff, who was so successful a collector of Crustacea, 

 though he records the common Lobster in his list of Moray Firth species, 

 does not appear to have observed the Copepod parasite which is so 

 intimately associated with that Crustacean. Nicothoe astaci is no doubt 

 frequently overlooked, and if a careful examination were made of the 

 lobsters captured on our shores the distribution of the parasite in the 

 Scottish seas might be found to be co-extensive with its host. 



The Nicothoe seems to be a remarkably sluggish animal. Milne-Edwards 

 — quoted by Dr. Baird* — states that "they allowed themselves to be torn 

 to pieces without making the least movement or quitting their hold," 

 and further, that though " taken carefully off the gills of the lobster with 

 all possible precautions not to injure the animals, and placed in a glass of 

 sea- water, though watched for several hours, and though they lived during 

 that period, as might be seen by the peristaltic movement of the intestine, 

 they made no attempt themselves at locomotion." I may add that my 

 son has kept specimens of Nicothoe alive for five weeks in ordinary sea 

 water, which was changed about once a week, and though they were care- 

 fully watched during that time he never saw them make any attempt to 

 move about, and the only indication that they were alive was the 

 persistence of their semi-transparent pinkish colour and the peristaltic 

 movement of the alimentary canal. The parasite is usually brightly 

 coloured, and, as it is of moderate size, is readily observed in situ when 

 that part of the lobster's carapace which covers the gills is removed. 



* British Entomostraca, p. 304. 



