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Show 1884.] HYBRIDS AMONG THE SALMONIDAE. 589 Male 21 lb. weight. Female 15 lb. weight. TV ± . inches. inches. Diameter of eye 0*9 0*8 Eye from end of snout 3-3 2*0 Eyes apart 2*6 2*0 Number of caecal pylori 52 52 Sexual differences.-The male had the milt well developed ; the knob on the lower jaw large, and on the mouth being closed it pressed against the palate. Colours of male : Generally of a blackish colour, with numerous small and oval spots, most distinct on the upper three fourths of the body, but some large ones along the abdomen ; fins black. Colours of female: Spots larger than in the male and some appear to be red, dark along the back, but not so much so as the male ; belly silvery. Eggs well developed, and average 0*2 of an inch in diameter. Mr. Arthur says that it is remarkable that the male, living in clear brilliant lake-water, was of a black colour: it was netted along with sixty more males and females of about similar dimensions. The outline of the back is "hog-backed" between the head and the dorsal fin, while the belly is very full, the tail slightly truncated, the other fins of the usual size, and the adipose very large. The longest pyloric caeca in each fish were 3 inches, the shortest 1 inch. Male. Female. Premaxillaries, extreme length of limb 2-0 inch. I*1. inch. „ number of teeth in each 9 6° size of largest teeth 0"25 inch. 0-15 inch. Maxilla, its extreme length 3-6 2*6 ,, its extreme width 05 " 0'25 „ no. of teeth in each 21-24* 13 size of largest teeth 015 inch. 045 inch. Mandible, no. of teeth each side 15 14 „ size of largest teeth 0"25 inch. 047 inch. Vomer, no. of teeth 2 0 Tongue, no. in each row 4 3 In the male there was as a rule a second or new tooth adherent to the gums along the inner side of each in the premaxillaries ; the teeth in the maxillae were irregularly placed, in more than one row in places, and with new ones in the gums. The two vomerine teeth were in a transverse row across the head of the bone; there were from 14 to 16 in each palatine. In the lower jaw the teeth were curved somewhat inwards, and the most posterior ones somewhat backward. The skin of the back was thickened and similar to what is generally perceived in old males in the breeding-season. Of course there are no means for ascertaining the precise age of these Trout; but the fact must not be overlooked that these fish are the progeny of eggs sent by Messrs. Buckland and Francis from Hampshire and Buckinghamshire streams, and which could not exceed fifteen years of age, while their appearance coincides with what would be termed Salmo ferox in Scotland or Ireland. I may here allude to the caecal appendages, respecting the number of which as consti- 40* |