198 SALMONIDiE OP BRITAIN. 



example 14 inches long from Loch Mulach Covric, there arc two teeth on the hind 

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

 bone. 



IIow the jaws in male trout and those of some of these fishes under certain 

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

 ol'ten larger than in females, are questions ■which may woll be deferi-ed until 

 considering the siTbjcet of the Lochlevcn trouts. The knob on the upper end of 

 the extremity of the lower jaw becomes v^cU dcveloised 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 sti'cams are most developed, 



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

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

 fish that arc in good health. The first dor.sal (except in old breeding males), 

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

 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 i'a\'ed 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 21 in the entire length of the fish,t or a similar 

 cxtrnt to what is jn-escnt in the sea trout {see pp. 1G9, 170 ante), disproving the 

 statement alluded to {see i-emarks of Dr. M'Intosb, 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 68 + x vertebra) and the first dorsal ray was 

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

 length of the fish, or as long as the postorbital jaortion, 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 throughouUife." iS'. stomdchiciis, vomer with a double series along its body, persistent. 

 iS'. niprlpinnie, transverse series of teeth across base of head of vomer, and in a single row along 

 the body, persistent. S. levcnensis, row across base of head of vomer, a single scries along its 

 body, persistent through lite. S. gdllircnsit: and .S'. orcndcnsis, 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 dilficult to account for. 



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

 in April, 188.5. Male, 10 lb. weight, 20| inches long, length of head 4i, height of body 31 in the 

 total length, lii/es — diameter one-seventh of the length of the head, 2^ diameter's 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 Gj in the 

 total length. Vertebrre 5(5. 58 ca^cal appendages, the longest being 28 inches. Lateral-line 

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

 salmon. In a female 10-2 inches long, length of head 4, height of body 4 in the total length. 

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



2 diameters apart. The mandible reaches posteriorly to § 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 vertebra' ; 54 cacal appendages, the longest of which was 1'9 inches. Lateral-line with 116 

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

 by Mr. Arthur in 1883 from New Zealand, the mule was 32.J inches long, the length of the head 5, 

 of caudal fin 7, height of body about 4i in the total length. Ei/es — diameter CJ times in the 

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

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

 12 between it and tlie 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. Ejiex — diameter about 4 in the length of 

 the head, and 1] diameters from the end of snout. Teetli — 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 Salmo ferox, yet all were brook trout. 



t 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. S. fario, Loch Mulach Corrie in a 

 male, 14-C in. long, 2; ; male, Howietoun, 14-G in., 2-i ; female, Loch Leven, 14-4 in., 2i; ; female. 

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

 2S ; female, 10-1 in. long, 2i ; male, 7'2 in. long, Stirlingshire, 2J ; and male, 6-5 in. long, 

 Gloucestershire, 2! in the total length. 



