470 
BULLETIN OF THE BUREAU OF FISHERIES 
From this fact and the size of the young secured during the spring and summer, these 
authors conclude that the eggs quite certainly are cast during the winter. 
Table 12. — Length frequencies of 1,151 young summer flounders, indicating that spawning probably 
begins in September and ends in April or May 
Length in milli- 
meters 
j Sept. [ 
Nov. | 
Dec. 
d 
c3 
>“5 
© 
Pn 
Mar. 
ft 
< 
| May 
June 
Length in milli- 
meters 
ft 
© 
m 
Nov. 
6 
© 
Q 
Jan. 
X5 
(-1 
CJ 
g 
| Apr. 
g 
| June | 
10 
87 
98 
14 
25 
6 
3 
1 
40-44 
1 
1 
Q 
3 
270 
237 
39 
45 
17 
8 
5 
45-49 
1 
8 
97 
60 
44 
13 
3 
50-54 
1 
3 
35 
55-59 
2 
1 
9 
60-64 
1 
65-69 
1 
70-74 
1 
35-39 - 
1 
DESCRIPTIONS OF YOUNG 
Ample specimens are at hand to show all the stages in the development of the 
larvae. The following descriptions and drawings have been prepared with the view 
of conveying to the reader a fair idea of the important stages in their development. 
Specimens 2.5 millimeters long.- — The recently hatched fish is compressed, deep 
anteriorly, and the caudal portion is relatively long and slender ending in a sharp 
point. At a size of 2.5 millimeters the head is decidedly deflected and proportionately 
very large, having a prominent hump, situated over and slightly behind the eyes, 
inclosing the brain. The mouth is large, strongly oblique to nearly vertical, and the 
joint of the mandible forms a sharp angle with the ventral outline. The visceral 
mass projects prominently, is loosely attached to the body, and the hind-gut is plainly 
visible posterior to the main visceral mass. A few very small dark chromatophores 
are visible along the ventral outline of the caudal portion of the body, and at a slightly 
larger size they appear on the visceral mass. An interesting structure is the relatively 
large pectoral-fin fold which becomes proportionately smaller as the fish grows, resulting 
finally in a comparatively small fin. It is interesting to compare this pectoral-fin 
development with that of the tonguefish, Symphurus plagiusa. The larvse of the 
tonguefish, too, have a rather prominent pectoral-fin fold, which, however, disappears 
entirely at a size of 10 to 12 millimeters. (Fig. 82.) 
Specimens of Paralichthys of this size are most readily recognized by the deep, 
compressed body, long slender tail, and large hump on the head. The row of dark 
spots, usually present along the ventral edge of the caudal portion of the body, also 
is helpful. 
Specimens 1+ millimeters long. — The advancement in the development over the 
2.5-millimeter specimen described in the foregoing paragraph is not pronounced. 
The head in the 4-millimeter fish is slightly less deflexed, the occipital hump is some- 
what smaller, and the mouth probably is a little less oblique. The dark chroma- 
tophores of the smaller fish have increased in size and number on the abdominal 
mass, and a few are now present on the back. The eyeball is slightly concave above 
and below and a little longer than deep in specimens of this size, as well as in smaller 
and in somewhat larger ones, as shown in the accompanying drawing. The base of 
a small fin at the nape (more fully developed at a slightly larger size) is just appearing 
in specimens 4 millimeters long. (Fig. 83.) 
The row of dark spots along the ventral edge of the abdomen, mentioned for 
the smaller stage, is now quite evident and, in combination with black chromato- 
