46. SALMONID.E COREGONUS. 297 



generally supposed. The species are highly valued for food, the flesh 

 being generally pale and of fine flavor. The coloration is very uni- 

 form ; bluish olivaceous above; the sides and below silvery. (*/;/'/?> 

 the temples; Y^'^I angle.) 

 This genus may be subdivided as follows: 



* Lower jaw included ; premaxillaries broad, placed vertically or tlio lower edge turned 



inward. 



t Gill-rakers short, thickish, few in number; preorbital broad, wider tliau pupil; 

 maxillary sbort aud rather broad, not reaching to the lino of the eye; the 

 small supplementary bone mostly narrow aud sharply elliptical ; mouth very 



small (PuosoPiUM Milner) coticai, williamsoni, quadrilateral-is, kenniootti. 



tt Gill- rakers numerous, long, and slender; preorbital long and narrow; maxillary 

 comparatively loug, the supplemental bone ovate. (CoiJEGONUS.) 



t Tongue too; bless, or nearly so; back elevated clupeiformis. 



Jt Tongue with about three scries of small teeth; body elongate, compressed. 



Idbradoricus. 



tit Tongue nearly toothless; back not elevated hoyi. 



** Lower jaw projecting; premaxillaru's narrow, placed more or less horizontally. 



Body elongate, snbfusiform; scales small, uniform, convex behind (ARGYKO- 



SOMCS Agassiz) merki, artcdi, niyripinnin. 



Body short, deep, compressed, shad-like; curve of the back similar to that 

 of the belly ; scales large, larger forwards, rather closely imbricated, the 

 posterior margin little convex ( ALLOSOMUS Jordan) tnUlbce. 



* Lower jaw included; preraaxillaries broad, placed vertically or turned inward. 



t Gill-rakers short, thickish, few in number; preorbital broad, wider than pupil; 

 maxillary short and rather broad, not reaching to the line of the eye; the 

 small supplementary bone mostly narrow and sharply elliptical ; mouth very 

 small. (Prosopium* Miluer.) 



46. C. COtaesii Miluer. Chief 3f on nialn Wliite-fmli. 



Head narrowed anteriorly, the snout prolonged, pig-like, protruding 

 beyond the mouth. Maxillary 4 iu head, barely reaching eye. Sub- 

 orbital and snpraorbital wider than in the other species. Depth 41 in 

 length; length of head about the same; body therefore elongate, not 

 elevated nor much compressed. D. 12; A. 10; scales 8-88-7. Chief 

 Mountain Lake, Montana, a tributary of the Saskatchawau. Very close 

 to the next, if really different; the head and mouth larger in the single 

 specimen known. 



(Miluer, Eept. U. S. Fish Com. 1872-'73, S3 : Prosopium couesi Miluer, in Jordan, Man. 

 Vert. cd. 2, 362.) 



487. C. wiflfllacmsoaaa Girard. Eocky Mountain White-fish. 



Body oblong, rather deeper than in C. qu'idrilatcmlis, but little com- 

 pressed. Head shortish, conic, the profile more abruptly decurved 

 than in the others. Snout compressed and somewhat pointed at tip, 

 which is entirely below the level cf the eye. Maxillary short and very 



* Miluer, in Jordan Man. Yert. ed. 2, 331: type C. ij_uudrilati:raUs Rich, (-^ 

 a mask; from the broad preorbital.) 



