DEVELOPMENT AND LIFE HISTORY OF SOME TELEOSTS 
585 
had appeared. Other color markings remained essentially as in the newly hatched 
larvae. The black color along the upper margin of the abdomen, described in the 
foregoing lines; the short black lines on the ventral surface of the tail, which remain 
as in the newly hatched fish; and the black chromatophores on the pectoral fins are 
very useful characters in identifying the larvae hatched in the laboratory with others 
taken in towing and described in the following pages. 
Specimens 1.5 to 2.0 mm long . — Although the newly hatched fish when alive, or 
before preservation, were around 2.7 mm in length, the smallest specimens taken in the 
tow are only 1.5 to about 2.0 mm long. These small larvae quite surely belong to the 
species under discussion. Their size does not exclude them, as young tender fish 
generally shrink greatly when preserved in formalin and alcohol. Young hatched in 
the laboratory, preserved when less than a day old in 65 percent alcohol, for example, 
decreased in length from about 2.7 to 2.0 mm. The specimens taken in the tow were 
killed in formalin and later transferred to about 75 percent alcohol. Some of these 
specimens, although 2.0 mm and less in length, evidently are several days old, as 
showm by the more advanced development. The older fish are less robust anteriorly, 
the pectoral fins are more elongate and less broadly rounded, and suggestions of rays 
are present. Indications of rays also are appearing in the vertical finfold around the 
tip of the tail. The color on the abdomen has become more concentrated along the 
upper margin of the abdominal mass, the black spots on the inner surface of the pec- 
Fiouee 85 . — Ilypaobtennius hentz. From a preserved specimen 3.0 mm long. 
torals are prominent, and the cross lines on the ventral edge of the caudal region 
remain as in younger fish. 
Specimens 2.5 to S.O mm long . — The head and trunk are robust, the head being 
about two-thirds as broad as deep. The head and trunk have become longer in 
proportion to the tail, the distance from tip of snout to vent being contained about 
2.4 times in the total length without the caudal finfold. The snout is very short 
and blunt, scarcely longer than the pupil, the forehead is very steep, and the mouth 
is slightly inferior, moderately oblique, with the tip of the lower jaw a little below the 
level of the middle of eye. Three minute preopercular spines are evident in some 
specimens. The vertical finfold remains continuous, with indications of rays pos- 
teriorly. The pectoral fins are long and rather narrow, with definite rays, and about 
three-fourths as long as the head. The most prominent color marking is an oblique 
black bar extending from the axile of the pectoral to the ventral outline just in front 
of the somewhat protruding hindgut. Several dark dots are present on the ventral 
surface in advance of the vent, a distinct dark bar crosses the forehead between the 
eyes, and generally several chromatophores are present on the upper surface of the 
head and nape. A row of small, vertically elongate, dark spots is situated on the ven- 
tral outline of the tail. The most important color markings for the purpose of identi- 
fication are dark dots, covering most of the pectoral fins, which extend to the tips 
of at least some of the rays (fig. 85). 
