THE WHITEFISHES OF NORTH AMERICA. 289 



I. Head long and sharp, 4 in length of body ; body very slen- 



der, the depth 5 to 6 in the length; maxillary 3 in 

 head osmeriformis, 9. 



II. Head long, 4k to 5 in length of body ; body deeper and head 



less pointed ; pectorals short, reaching about half way 

 to ventrals. 

 in. Maxillary 3£ to 3f in head; lower jaw projecting beyond 

 upper; gillrakers long and numerous, usually about 



47 on first gill-arch artedi, 10. 



vim. Maxillary longer, 2? to 3 in head; lower jaw scarcely 

 or not at all projecting; gillrakers fewer, usually not 



more than 39 or 40 on first gill-arch hoyi, 11. 



///. Head shorter, about 5 in length of body; pectorals long, 

 reaching more than half way to ventrals; maxillary 



3£ in head pusillus, 12. 



kk. Eye small, shorter than snout, about 5 times in length of 

 head. 

 n. Head short, about 5 in length of body. 



o. Body rather slender, the depth about equal to length 



of head lucidus, 13. 



oo. Body deeper, the depth in adult greater than length 



of head laurettw, 14. 



nil. Head long, 4 to 4A in length of body; lower jaw 

 strong; maxillary very long, 2+ in head; mandible 

 also very long, usually reaching posterior edge of 



orbit, at least half as long as head prognathus, 15. 



jj. Lower fins all blue-black; body stout; mouth large; gill- 

 rakers numerous, usually at least 50 on the first 



gill-arch nigripinnis, 16. 



ii. Body short, deep, and compressed, the curve of the back similar 

 to that of the belly ; scales large, larger forward and 

 closely imbricated, the free margin often concave or 



notched tuilibee, 17. 



F . R . 94 19 



