Mr. Thompson on Fishes new to Ireland. 357 



Salmo ERiox,Linn., Bull Trout. — Dec. 3,1836. In Belfast 

 market I selected from a basket filled with sea trout (S. Trutta), 

 in high condition, three specimens of S. Eriox, which were 

 taken along with them in the sea at Donaghadee in the county 

 of Down. Their length is from 19 \ to 21 inches ; weight of 

 each about 2 j lbs. Two are males, having the lower jaw very 

 slightly hooked*, the other is a female; the operculum diifers 

 much in the sexes ; teeth on the vomer of one male and the 

 female three in number, in the other male four ; teeth gene- 

 rally much smaller in the female than in the males. Fin-rays 

 with one or two exceptions are in the three specimens — D. 14, 

 P. 14, V. 10, A. 11, C. 19. 



In colour they are silvery grey, having but few spots (of the 

 form xxx and purplish black) above the lateral line and 

 scarcely any below it. Donovan's Sewen (pi. 91.), with which 

 they are evidently identical, is a very characteristic figure. 

 These specimens differ only from it in having fewer spots 

 below the lateral line — but in this particular they accord not 

 with each other — and in the darkness of the blue he represents, 

 being relieved or lightened by a silvery castf. The tail of the 

 sewen cannot be called incorrect from being forked, as when 

 unexpanded it appears slightly so in the present specimens, 

 although when fully spread out it is square. The female ex- 

 hibits over the body and operculum, &c. as many more spots 

 as the males — on her operculum are six round spots, on that 

 of the males two or three. Fins of the female coloured as in 

 the sewen, but in the males all darker ; V. and A. dull pink or 

 flesh colour in the female; in the males the V. grey for two thirds 

 posteriorly, the A. entirely dark grey ; their other fins merely 

 of a darker shade than those of the female. Irides sil- 

 very. 



The ova in the female are very minute, being not more than 

 half the size of clover seed ; the milt in the males occupies 

 twice its space. These latter not having any of the red mark- 

 ings said to distinguish the adult male, and the hook of the 



* In the ' Fauna Boreali Americana' it is remarked, that " the hook of 

 the under jaw is very decided, even in a young Salmo Cambricus," (Part 3. 

 p. 307,) but in the present instance the reverse appears. 



f This observation is perhaps superfluous, as different copies of the work 

 may not invariably exhibit the same shade of colours. 



