44 SALMONIDyE. 



inches. 

 Distance between eye and angle of praeoperculum . . ^ 



Greatest width of operculum -j^^ 



Greatest depth of operculum |- 



Distance between occiput and origin of dorsal fin . . 3 



Distance between end of dorsal and root of caudal . . 4 



Length of base of dorsal 1^ 



Greatest height of dorsal 1|^ 



Length of pectoral 1^ 



Distance between root of pectoral and root of ventral 2f 



Length of ventral fin 1^ 



Distance between root of ventral and origin of anal . . 1^ 



Length of anal fin 1 



Greatest depth of anal 1-A- 



Length of longest caudal ray Ij 



Length of middle caudal ray -f 



The greatest depth of the body is below the origin of the dorsal 

 fin, and is contained four times and a half in the total length (with- 

 out caudal) ; the length of the head bears about the same proportion. 

 The snout is moderately produced, conical, and contained twice in 

 the postorbital length of the head ; the lower jaw is without hook, 

 the mouth closing perfectly ; the maxillary bone is longer than the 

 snout by about three-fourths the diameter of the eye, and does not 

 reach quite to the vertical from the hinder margin of the orbit ; the 

 width of its broadest part is about half the diameter of the eye. 



The dentition of the jaws and palate is perfect, the mandibulary 

 teeth being slightly larger than those of the intermaxillary and 

 palatines, which are equal and, again, slightly exceed the maxillary 

 teeth. The body of the vomer is armed with six teeth, which form 

 a single series, and arc rather remote from one another, the last 

 being not far from the hinder extremity of the bone. The inter- 

 orbital space is convex, the orbit being slightly below the upper pro- 

 file of the head : the width of this space is one-eighth of an inch 

 shorter than the maxillaiy bone. The praeoperculum has the hinder 

 margin, angle, and lower limb I'ounded, the latter being very dis- 

 tinct ; the posterior margin of the operculum is very slightly 

 rounded, and placed nearly at right angles to its lower Hmb ; the 

 angle of the suboperculum is rounded. A line taken from the upper 

 end of the gill-opening to the angle of the operculum is equal to the 

 length of another line from the latter point to the lower end of the 

 suboperculum. 



The distance of the origin of the dorsal fin from the occiput exceeds 

 by one quarter of an inch the distance of its posterior end from that 

 of the adipose, and equals somewhat more than two-thirds of its 

 distance from the root of the caudal fin. The dorsal fin is nearly as 

 long as high, and composed of fourteen rays, of which the first two 

 are rudimentary and enveloped in the skiii, the third simple and 

 about half as long as the fourth, which is also simple ; the fourth, 

 fifth, and sixth rays are nearly oqnal in height, the fifth being the 

 firtft branched ray. The last ray is cleft to the base. 



