4 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Dr. Bean now regards this fish as distinct; be was never fully satisfied with the 
identification of these specimens with C. hoy i, and so expressed himself some years ago. 
The paucity of material, however, anu the somewhat indefinite or confused published 
descriptions, to which he alludes in the paragraph quoted, deterred him from attempt 
iug a final settlement of the question. 
COREGONUS PROGNATHUS, sp. uov. 
Argyrosomus hoyi, Miluer, Rej)t. U. S. Fisli Comm., 1872-73, 86. Outer Islaml, Lake Superior. 
(Not Argyrosomus hoyi Gill.) 
Body oblong, much compressed, back elevated, tapering rather abruptly toward 
the narrow caudal iieduucle, the adult fish having a slight nuchal hump as in C. 
clupeiformis-, greatest depth 3^- to 4 in body length. Head rather short and deep, 
pointed, 4 to 4.|- in length; gi’eatest width half the length; cranial ridges prominent. 
Snout straight, its tip on level wdth lower edge of pupil. Top of head 2 in distance 
from occiput to front of dorsal. Mouth large and strong; maxillary reaching to oppo- 
site middle of pupil, 2^ in head, length 3 times its width; mandible long, projecting 
beyond upper jaw when month is closed, reaching to or beyond posterior edge of eye, 
If to l-§ in head. Eye small, 5 in head, in snout, 1^ in iuterorbital space, in 
suborbital space. Gill-rakers slender, about length of eye, 13 above and 25 below 
angle. Adipose fin the length of eye, its width half its length. Narrowest part of 
caudal peduncle contained nearly four times in greatest body depth. Dorsal rather 
high, with 9 or 10 developed rays, the longest one-half longer than base of fin and 
contained If times in greatest body depth, 3J times in distance between dorsal and 
snout, and 1^ times in head ; free margin slightly concave; origin midway between end 
of snout and base of caudal; dorsal base opposite 9 scales. Anal with 10 to 12 devel- 
oped rays; the longest ray equal to base of fin and two-thirds height of dorsal. Yeu- 
trals as long as dorsal is high; their origin midway between anterior edge of orbit and 
base of caudal. Ventral appendage short, covering about 3 scales. Pectorals as long 
as ventrals. Scales rather large, about 75 in lateral line, 7 or 8 above the lateral line, 
7 or 8 below the lateral line. Lateral line straight except at origin, where it presents 
a rather marked curve. Sides of body uniformly bright silvery, with pronounced bluish 
reflection in life; the back dusky, the under parts pure white without silvery color. 
Above lateral line, light longitudinal stripes involving central part of scales extend 
whole length of body. Fins flesh color or pinkish in life, the dorsal and caudal 
usually showing dusky edges. Postorbital area with a bright golden reflection. Iris 
golden, pupil black. Branchiostegals, 8. Average length, 15 inches. 
Habitat: Lake Ontario, Lake Michigan, Lake Supeiior, and doubtless the entire 
Great Lake basin, in deep water. 
' Etymology: Frognathits, from npo, before, and yvddo?, javr, in allusion to the 
projecting mandible. The fish is called “long-jaw” in lakes Michigan and Ontario. 
This species is based on 8 specimens from lakes Sui^erior and Michigan in the 
collection of the U. S. National Museum and 17 s]>ecimens from Lake Ontario in the 
collection of the U. S, Fish Commission. The examples in the museum are as follows: 
Seven from Outer Island, Wis., Lake Superior, collected by J. W. Miluer (catalogue 
numbers 1057G and 35344), and one from Petosky, Mich., Lake Michigan, collected by 
McCormick and Connable (catalogue number 23540). The fish in the possession of 
the Pish Commission were received in the flesh in 1892. One lot, consisting of 11 
