1884.] HYBRIDS AMONG THE SALMONID^. 589 



Male 21 lb. weight. Female 15 lb. weight, 

 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'J inch. 



„ number of teeth in each 9 6 



„ size of largest teeth 0-25 inch. 0-15 inch. 



Maxilla, its extreme length 36 „ 2*6 ,, 



,, its extreme width 05 ,," 0'25 



„ no. of teeth in each 21-24 13 



„ size of largest teeth 0'15 inch. 0-15 inch. 



Mandible, no. of teeth each side 15 14 



„ size of largest teeth 025 inch. 0'17 inch. 



Vomer, no. of teeth 2 



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 Buckinghamsliire 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* 



