132 SALMONID^. 



depth of tlie tail equals the length of the base of the dorsal fin. The 

 height of the head above the mandibulary joint equals the distance 

 bet^\-een the posterior margin of the orbit and the end of the oper- 

 culum. The upper profile of the head is somewhat elevated above 

 the margin of tl;e orbit, the diameter of which is nearly one-fifth of 

 the length of the head, shorter than the snout, and more than one- 

 half of the width of the interorbital space ; the latter is very di- 

 stinctly convex, with a rather prominent ridge along the middle, and 

 with a pair of series of pores. Snout slightly compressed, subconical, 

 with the jaws equal anteriorly. The nostrils are situated imme- 

 diately before the eye ; the posterior is the wider, and the cutaneous 

 bridge between the two is not developed into a flap. The maxillary 

 extends scarcely beyond the vertical from the posterior margin of the 

 eye, and is armed with 20-21 teeth of moderate size ; four teeth in 

 the intermaxillary, seventeen in each mandible, two pairs on the 

 vomer, fifteen on each palatine bone, and four pairs on the tongue. 

 The suhoperculum forms the hindmost part of the gill-cover, and 

 does not cover the exposed portion of the humerus above the root of 

 the pectoral ; its vertical width is rather less than one-half of that 

 of the operculum, and therefore is comparatively narrow. Nearly all 

 the hranchioster/als are situated at the side of the head, and ex- 

 posed in a lateral view of the fish. The lower branch of the outer 

 branchial arch is provided with eleven lanceolate, slightly curved 

 gill-rakers ; the longest is less than two lines long in the specimen 

 described. 



The origin of the dorsal fin is exactly in the middle between the 

 snout and the root of the caudal ; the length of its base is equal to the 

 length of the last ray, and contained once and three-fourths in that 

 of the fourth ; the fourth and fifth rays form an acute point, and 

 the upper margin of the fin is straight ; the first ray is rudimentary, 

 the second half as long as the third, tlie third three-fifths of the 

 fourth, the fourth simple, the fifth branched, fourth and fifth longest, 

 the last split to the base. The distance of the adipose fin from the 

 dorsal is equal to twice and a third the base of the latter. 



The origin of the anal fin is exactly in the middle between the 

 root of the caudal and that of the outer ventral ray ; the length of 

 its base equals that of the dorsal, and is contained once and two- 

 thirds in the length of the fifth ray. The five anterior rays are en- 

 veloped in a common membrane, so that their length can be ascer- 

 tained only by dissection ; the fourth and fifth rays are the longest, 

 and form an acute point ; the lower margin of the fin is nearly 

 straight. The first ray is rudimentary, the second half as long as 

 the third, the third three-fourths of the fourth, the fourth simple, 

 the fifth branched ; the last split to the base, its length being two- 

 fifths of that of the fourth. 



Caudal fin forked, one of the middle rays being half as long as the 

 outer ones, the length of which is contained five times and a half in 

 the total. Lobes pointed. 



The base of the pectoral is entirely free, and not overlapped by 

 the gill-cover apparatus. It does not extend to the vertical from the 



I 



I 



I 



