198 SALMONID^ OP BRITAIN. 



example 14! inches long from Locli Mulach Corrie, ttere are two teetli on the Hnd 

 edge of the head of the vomer and twelve still remaining along the body of that 

 bone. 



How the jaws in male trout and those of some of these fishes nnder certain 

 conditions are stronger than is usually the case, and how the teeth of males are 

 often larger than in females, are questions which may well be deferred until 

 considering the subject of the Lochleven trouts. The knob on the upper end of 

 the extremity of the lower jaw becomes well developed in old specimens as already 

 described* (see p. 186 ante). 



Fins — although as quoted in a note (p. 13), Dr. Giinther denied Agassiz's 

 statement that the fins of trout inhabiting rapid rocky streams are most developed, 



1 find some to be so among a large number of specimens examined : while 1 

 do not find that in these places the extremities are worn off, at least in 

 fish that are in good health. The first dorsal (except in old breeding males), 

 as a rule, commences somewhat nearer to the snout than to the base of the upper 

 caudal ray ; the height of the anterior ray usually exceeds the length of the fin's 

 base. Origin of adipose dorsal fin about midway between the anterior insertion of 

 the base of the rayed dorsal and the superior extremity of the upper caudal lobe, 

 or the distance from the front end of the snout to the commencement of the base 

 of the dorsal fin, equals about 2f in the entire length of the fish,t or a similar 

 extent to what is present in the sea trout (see pp. 169, 1?0 ante), disproving the 

 statement alluded to (see remarks of Dr. M'Intosh, page 170), that the dorsal fin 

 in the fresh-water races is decidedly further forward than in the marine forms. 

 An example from Loch Ard, had 58 + a; vertebrce and the first dorsal ray was 

 connected to the neural spine of the 15th vertebra. Pectoral from 6 to 7f in the 

 length of the fish, or as long as the postorbital portion, or of even the entire head 

 excluding the snout, in some examples it is more pointed than it is in others. 

 Having measured a large number of examples from rivers and lochs, as a rule, 



persistent thronghouyife." S. stomacJiicus, vomer with a double series along its body, persistent. 

 S. nigripinnie, transverse series of teeth across base of head of vomer, and in a single row along 

 the body, persistent. 8. levemmis, row across base of head of vomer, a single series along its 

 body, persistent through life. S. gallivensis and 8. orcadensis, teeth on vomer in a single series, 

 persistent. The above show how some authors have merely examined young or moderately aged 

 specimens, for in all very old ones the vomerine teeth drop out with age as I have figured. How 

 conclusions have been come to from the examination of young fish, that the vomerine teeth are 

 persistent throughout life, it is difficult to account for. 



* Mr. Arthur kindly sent me a pair of specimens of New Zealand trout from the Pomahaka river, 

 in April, 1885. Male, 16 lb. weight, 20f inches long, length of head 4J, height of body 3J in the 

 total length. Eyes — diameter one-seventh of the length of the head, 2J diameters from the end of 

 the snout, and the same distance apart. The maxilla reaches posteriorly to half a diameter 

 behind the orbit. Vomer with two teeth on the hind edge of its head. Pectoral fin 6f in the 

 total length. Vertebrae 56. 58 csecal appendages, the longest being 2-8 inches. Lateral-line 

 with 111 scales and 14 rows between the adipose dorsal fin and the lateral-line. Flesh red as a 

 sahnon. In a female 19'2 inches long, length of head 4, height of body 4 in the total length. 

 Eyes — diameter one-seventh of the length of the head, 2 J diameters from the end of the snout, and 



2 diameters apart. The mandible reaches posteriorly to f of a diameter behind the orbit. Vomer 

 with one tooth which fell out on the skull being macerated. Pectoral fin 7 in the total length. 

 56 vertebras ; 54 Cfflcal appendages, the longest of which was 1-9 inches. Lateral-line with 116 

 scales, and 13 rows between it and the adipose dorsal fin ; flesh, white. In another pair also sent 

 by Mr.^ Arthur in 1883 from New Zealand, the male was B2J inches long, the length of the head 6, 

 of caudal fin 7, height of body about 4J in the total length. Eyes — diameter 6J times in the 

 length of the head, 3 diameters from the end of the snout. The maxilla reaches to f of a 

 diameter behind the orbit. Teeth — absent from the vomer. Lateral-line — 118 rows of scales, 

 12 between it and the adipose dorsal fin. In a female 31 J inches long, the length of the head 5, of 

 caudal fin 7, height of body about 5 in the total length. Bj/es— diameter about 4 in the length of 

 the head, and IJ diameters from the end of snout. Teeth — some at the hind edge of head of vomer. 

 Lateral-line — 120 rows of scales, 14 between it and the adipose dorsal fin. AU the foregoing four 

 fish are what would be termed Balmoferox, yet all were brook trout. 



•j- The following are proportional measurements made in the distance from the front edge of 

 the snout to the commencement of the base of the dorsal fin. 8. fario, Loch Mulach Corrie in a 

 male, 14-6 in. long, 2J ; male, Howietonn, 14'6 in., 2J ; female. Loch Leven, 14-4 in., 2J ; female. 

 Loch Ard, 11-3 in., 2J ; female, Eiver Lossie, 10-4 in. long, 2J ; male, 10-2 in. long, Gloucestershire, 

 2i ; female, lO'l in. long, 2J ; male, 7'2 in, long, Stirlingshire, 2J ; and male, 6-5 in. long, 

 Gloucestershire, 21 in the total length, 



