584 
BULLETIN OF THE BUREAU OF FISHERIES 
days. The fish presumably did not feed, but it is quite unlikely that they died of 
starvation as a bit of the yolksac remained even in those individuals that lived longest. 
Newly hatched fish . — The newly hatched fish range in length from about 2.6 to 
2.8 mm. The yolk is nearly all absorbed at hatching. The fish are robust anteriorly, 
with a broad depressed head. The tail is long and slender, with the vent situated 
much in advance of midbody length; distance from snout to vent about 1.0 mm, from 
vent to tip of tail, without finfold, about 1.5 mm. The snout is short and very blunt; 
the eye is large, having a diameter of about a quarter of a millimeter; the mouth is 
large, the gape reaching to or past the middle of eye. Large pectorals with suggestions 
of rays are present. The body is fairly transparent. Consequently the outline of 
the brain and the circulation can be seen rather definitely. The aorta may be seen 
close to the notochord, turning upon itself about an eye’s diameter from the tip of 
the tail to form the caudal vein. Heart action is too rapid to permit accurate enu- 
meration of the beats. However, the number of beats probably is close to 230 per 
minute. About 28 to 30 myomeres may be enumerated, being indefinite in advance 
of the vent (only 3 or 4 visible) and again toward the tip of the tail. The vertebrae 
count in the adult is 33, there being 9 body and 24 caudal ones. The number of more 
or less definitely outlined myomeres in the newly hatched fish, therefore, is not far 
below the number of vertebrae in the adult. 
Figure 84 . — Ilypsoblennius hentz. From newly hatched fish. Length of live specimen 2.6 mm. AV, auditory vesicle. (Drawn 
by Nell Henry.) 
Several dark markings are present on the newly hatched fish which correspond for 
the most part with those already present in the advanced embryo as described else- 
where. The eye is very dark with a greenish sheen above the pupil; an irregularly 
outlined dark spot is present on the head between the anterior part of the eyes, or in 
some specimens several black chromatophores are distributed over the snout to the 
interorbital ; generally a blackish blotch with branches is present at the auditory vesicle ; 
many black chromatophores (or in some specimens in part solid black) are present 
on the abdominal region; and the ventral side of the tail is marked by short black 
branching cross fines. The large pectorals are marked on the inner surface, with 
dark chromatophores. The dark markings often are present only on the basal two- 
thirds, although sometimes they may cover nearly the entire inner surface and extend 
to the margin of the fin (fig. 84). 
Comparatively few of the numerous fish hatched lived as long as 2 days. At 2 
days after hatching the fish apparently had become more slender and had increased 
in length only slightly, being 1 .8 to 1 .9 mm long. The yolksac was almost all absorbed. 
Only minor changes in color had taken place. The black chromatophores on the 
abdominal region had become more concentrated along the side near the upper 
boundary of the abdomen in the form of an indefinitely outlined oblique band extend- 
ing from near the eye to the vent. Only a few separate black branched markings 
remained on the ventral surface of the abdomen (yolksac) where a shade of yellow 
