1. SALMO. 33 



inches. 



Length of the maxillary bone If 



Distance between eye and angle of praeoperculum . . 14 



Greatest width of operculum f 



Greatest depth of operculum 1-^ 



Distance between occiput and origin of dorsal fin . . 5|- 



Distance between end of dorsal and root of caudal . . 6X 



Length of base of dorsal l|: 



Greatest height of dorsal If 



Length of pectoral 2-^ 



Distance between root of pectoral and root of ventral 4|- 



Length of ventral fin If 



Distance between root of ventral and origin of anal . . 3^ 



Length of anal Ig 



Greatest depth of anal If 



Length of longest caudal ray 2^ 



Length of middle caudal ray If 



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

 fin, and is contained four times and two-thirds in the total length 

 (without caudal) ; the length of the head four times and a quarter. 

 The snout is produced, pointed, and three-fifths of the length of the 

 postorbital part of the head, or five-sixths of that of the maxillary 

 bone ; the mandible has scarcely a trace of a tubercle at its extremity, 

 and the jaws can be brought into perfect contact. The maxillary 

 bone is longer than the snout by half the diameter of the eye, and is 

 not very strong, its greatest width being less than two-thirds of the 

 diameter of the eye ; and it extends considerably behind the vertical 

 from the posterior margin of the eye. The teeth of the intermax- 

 illary and mandibular series are stronger and larger than those of 

 the maxillary and palatine bones. All the teeth of the vomer are 

 lost, except three, which occupy the hinder part of the head of this 

 bone. 



The distance of the nostrils from the orbit is somewhat less than 

 the diameter of the latter. The interorbital space is convex, the 

 eye being situated below the upper profile of the head • the width of 

 this space is equal to the length of the snout. 



The praeoperculum has the posteiior margin scarcely rounded, and 

 the lower limb horizontal : operculum and suboperculum very thin, 

 concentrically striated, the striae running parallel to the gill-opening ; 

 the posterior margin of the operculum is very slightly rounded, 

 meeting the lower limb at a right angle ; suboperculum of moderate 

 width, two-fifths as broad as long. The distance from the angle of 

 the operculum to the lower anterior end of the suboixircidum is 

 three-fourths of that from the upper end of the gill-opening to the 

 first-named point. 



The distance of the occiput from the origin of the dorsal fin, if 

 measured back from behind that fin, reaches three-fourths of the 

 space between the adipose and the root of the caudal fin. The dorsal 

 fin is longer than high, and possesses thirteen rays, of which the first 

 and second arc rudimentary, the third simple and much shorter than 



OL. VI. ^ 



