^PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 73 



beyond the eye ; opercle more prolonged backwards than in spilurus^ 

 making the head appear longer. Pectoral fins smaller than in spilurns. 



Scales small, silvery, 28-180-29. 



Caudal fin short, rather faintly forked, but more so than in spilurus. 

 Adipose fin rather small. Fins all small, the dorsal of the usual "sa- 

 lar^' pattern. 



Fin-rays : Dorsal, 2, 11. Anal, 2, 10. 



Color dark above] head, body, and upper fins with small, round, block 

 spots, very numerous, and nearly as close together before as behind; a 

 few spots on the belly in some specimens. 



Measurements of specimen: Length, 12 inches; depth, .23i of length 

 to base of caudal ; head, .24J ; interorbital width, .07 ; maxillary, .10 ; 

 mandible, .15; middle caudal rays, .11 ; outer caudal rays, .17. 



This species may be known from S. spihirus by the more forked tail, 

 the longer and slenderer head, and the greater spottiness anteriorly. 

 From aS'. irideus, it may be known by the much slenderer form, larger 

 mouth, longer head, and much larger scales ; from 8. henshmci, which it 

 most resembles, by the shorter head and by the lack of hyoid teeth; and 

 from ;S'. clarU, which it also resembles, by the want of hyoid teeth, and 

 other characters. 



These black spotted Salmon of the Eocky Mountain region and Pacific 

 slope belong to a well-marked group, for which the name Salar, Valen- 

 ciennes, may be retained as a subgenus of the genus Salmo. Although 

 not by any means so different from the true Salmo (type S. salar L.) as 

 are the genera Oncorhynchus, Cristivomer (type S. namaycushW-d\h.), and 

 Salvelinus (type 8. salvelinus L.), it is not impossible that future writers 

 may consi<ler Salar as a genus distinct from Salmo. The character of a 

 single instead of a double row of teeth on the shaft of the vomer, sup- 

 posed to distinguish Fario, Val., from Salar, has no generic value, and 

 probably not even a specific value, at least as hitherto stated. In all the 

 species properly referable to Salar, the teeth are arranged alternately, 

 each one pointing to the right or left, in an opposite direction from its 

 neighbor. These teeth are therefore in a sort of quincuncial row, which 

 in many or most instances appears as two distinct rows, and almost 

 always is divided into two anteriorly. Most of the " Salmon-trout" and 

 "Trout" of Europe and Asia belong to this group, ^^Salar^\ Although 

 most of the species referred to Fario belong to Salar, it is not certain 

 whether the type of Fario, F. argenteus Val., from France, is a Salar 

 or a true Salmo. The figure looks to me like a young Salmon {S. salar). 



The American species of the subgenus Salar which are now consid- 

 ered valid by Dr. Gill and myself may be compared as follows : — 



Common characters : — Eiver Salmon, not anadromous, with the vomer comparatively 

 flat and not boat-shaped, its form essentially as in Sahno proper, 

 the Yomerino teeth extending for some distance along the shaft of 

 the bone in two alternating rows or in one zigzag row, the teeth 

 divergent and directed somewhat forward, not deciduous: scales 



