With fifteen or less rays in the dorsal fin 52. 



52. With eight to ten branchiostegals; seldom over twelve inches long; as' 



cending streams from the Atlantic and Pacific; Family Osmeridae 

 Smelts 53. 



With ten or more branchiostegals; often larger; lake species; Family 

 Coregonidae Whitcfish and Lake Herrings 55. 



53. With twenty-one rays in the anal fin; northern Pacific slope 



Thaleichthys paaficus (Richardson) Candlefish 

 With fourteen to si.xteen rays in the anal fin 54. 



54. Pectoral fins reaching about to the insertion of the pelvic fins; ascending 



streams from the Pacific 



Spirinchus thaleichthys (Ayres) Pacific Smelt 

 Pectoral fins much shorter; ascending streams from the Atlantic, often 

 landlocked 



Osmerus mordax (Mitchill) American Smelt, Icefish 



55. Upper jaw extending scarcely, if any, beyond the lower jaw; Great 



Lakes and surrounding territory Lake Herrings (Several species, 

 only the most common of which are given here. For details of this 

 group, see Koelz, 1931, Papers Mich. Acad. Sci., Arts and Letters, 13 

 (1930) ) 56. 



Lower jaw conspicuously overhung by the upper which has the pre' 

 maxillaries turned downwards 59. 



56. Lower jaw projecting noticeably beyond the upper; tip of lower jaw 



usually with a symphyseal knob 



Leucichthys hoyi (Gill) Cisco, Bloater 

 Jaws almost equal 57. 



57. Usually with less than forty gill rakers on the gill arch; lower jaw pale 



Leucichthys zenithicus (J. 6? E.) Short-jawed Chub 

 Usually with more than forty gill rakers on the gill arch; lower jaw pig' 

 mented, at least toward the tip 58. 



58. Body deepest anteriorly 



Leucichthys nigripinnis (Gill) Blackfin 

 Body deepest through the middle 



Leucichthys artedx (LeSueur) Common Lake Herring 



59. With 17 to 20 gill rakers on the lower section of the first gill arch 



(below the bend) ; body much compressed; Great Lakes 

 Coregonus clupeaformis (Mitchill) Whitefish 

 With 12 to 16 gill rakers on the lower section of the first gill arch; 

 body not so much compressed 60. 



60. Base of adipose fin as long as the base of the anal fin; Columbia River 



valley 



IriUion oregonius (J. ^ S.) Chisel-mouth Jack 

 Base of adipose fin shorter (Several species, of which the two most widely 

 distributed are given) 61. 



61. Upper jaw not reaching to below the front of the eye; New England to 



the Great Lakes 



265 



