SIXTY-TWO SPECIES OP FISHES FROM LAKE ERIE 
307 
probably about 28 to vent, plus 16 behond. Body very slender and elongate with 
bulbous forehead; terminal mouth placed very low, with gape to front margin of pupil; 
pectorals developed by unrayed ; marginal fin fold arising dorsally at about sixteenth 
myomere behind head, low, but slightly higher above vent, very low around caudal, 
and continued on underside forward past vent to middle of intestine. Although 
the notochord still is straight, lower caudal rays are developing. 
Pigmentation. — Body is colorless except for partially pigmented eyes. 
Although the myomere count is somewhat shorter, there are certain very impor- 
tant characters of this larva which seem to indicate that it is identical with the species 
Figure 3 . — Hiodon tergisus, 6.5 millimeters 
represented by the 14.2-millimeter specimen, which is the subject of the next descrip- 
tion. The exceptionally protruding snout, very large mouth, small eye, elongate body 
with vent situated far back, posterior insertion of dorsal marginal fin fold with slight 
elevation above vent, unusually low marginal fin fold around caudal with rays forming 
in this fin before the notochord bends upward, all point to its identification as Hiodon 
tergisus. The very early stage of the larva may account for the incompleteness of 
myomeres, and thus it is tentatively assigned to this species. 
14 -2-millimeter stage . — Total length, 14.2; standard length, 13.2; length to vent, 
9.0; length of head, 2.5; snout, 0.6; diameter of eye, 0.85; greatest depth before vent, 
2.0; depth behind vent, 1.0 millimeter. Myomeres, 30 to vent plus 21-23 behind. 
Contour of dorsal fin indicated with elements of 12 dorsal rays and about 20 anal 
Figure 4 . — Hiodon tergisus, 14.2 millimeters 
elements apparent; lower caudal rays developed although tail not yet completely 
heterocercal. Slender, oblong body; blunt snout much protruding, so that mouth is 
inferior; lower jaw included; premaxillaries and maxillaries very slender; gape of 
mouth to distal margin of pupil ; wide set, cardiform teeth in premaxillaries, and man- 
dibles proportionately larger at this state than in adult; nostrils large, close together. 
Pigmentation. — Brownish chromatophores appear on the ventral surface below 
the large, anteriorly placed oil globule, and along yolk region a quarter of the distance 
to vent. A few widely separated subsurface spots are present along dorsal aspect of 
stomach region. An irregular double line of small chromatophores is seen on dorsal 
margin from dorsal fin to caudal, and a single partially subsurface series on ventral 
margin from shortly behind vent to caudal. Small pigment spots are distributed at 
base of caudal. 
109774°— 32 2 
