DEVELOPMENT AND LIFE HISTORY OF SOME TELEOSTS 
597 
generally several dark chromatophores occupy the ventral edge of the abdomen, 
besides a few to several dots which are variously distributed. Dark bars, appearing 
as spots in a lateral view, are present on the ventral edge of several of the caudal 
myomeres in some specimens, and on most of them in others. The large eyes are black 
with a greenish sheen over the pupil. The newly hatched fish swims or floats on its 
back and is very active (fig. 102). 
The fish hatched in the laboratory lived only about 2 days. No change worthy 
of note, except that the color on the abdomen became more diffuse, took place in 
the meantime. 
Newly hatched larvae of this species are a little smaller (length 2.4 mm) than those 
of Hypsoblennius hentz (length 2.7 mm). The larvae of the latter species are also 
rather more stocky anteriorly. Furthermore, the black marks on the abdomen appear 
as separate branching chromatophores and are quite generally distributed, whereas in 
H. geminatus the black is concentrated mostly on the side near the upper margin of the 
Figure 102 .— Hypleurochilus geminatus. From a newly hatched fish 2.4 mm long when alive. A V, auditory vesicle. 
Figure 103 . — Hypleurochilus geminatus. From a preserved specimen 1.6 mm long. This larva is smaller than the newly hatched 
live fish (Fig. 102) quite certainly because of shrinkage in preservative. 
abdominal mass into almost solid black with only a few scattered chromatophores 
elsewhere. In H. hentz most of the inner surface of the pectoral fin membrane is 
dotted with black branching chromatophores, whereas in H. geminatus only a few 
black dots at most are present at the base of this fin. 
Specimens 1 .5 mm long . — The head and trunk in preserved specimens of this size 
are short and rather robust, while the tail is long, rather slender and compressed, the 
head and trunk being contained about 2.4 to 2.9 times in the total length without the 
caudal finfold. The snout is very short and round, scarcely extending beyond anterior 
margin of eye. The mouth is small, oblique, and terminal, with the tip of the lower jaw 
slightly below the level of the middle of the eye when the mouth is closed. The 
vertical finfold is continuous and without rays. The pectoral fins appear as mere 
tufts of membrane, scarcely longer than the pupil and the ventral fins are not evident. 
An oblique dark bar extends from the axileof the pectoral to the ventral outline just 
above the vent; the ventral surface of the chest and abdomen generally is marked with 
a few to several dark points ; and a distinct dark bar crosses the forehead between the 
eyes. A rather close-set row of fine, vertically elongate, dark spots is present on the 
ventral outline of the tail, and the base of the rudimentary pectoral is mostly black 
(fig. 103). 
