448 
BULLETIN OF THE BUREAU OF FISHERIES 
Specimens 45 millimeters long. — At this size the fish virtually has all the char- 
acters of the adult. While the body acquires essentially the shape and form of the 
adult at a much smaller size, the adult colors are not acquired until the fish attains 
a length of about 40 to 50 millimeters. At about this range in size the back becomes 
dark bluish, the sides silvery, and the underneath parts pale. In the meantime, 
the dark chromatophores, present on the body in smaller fish, have disappeared. 
The pectoral fin has increased further in length and now reaches well past the origin 
of the dorsal, although not opposite the middle of the dorsal as in the adult. Two 
dermal flaps attached to the tip of the lower jaw, first noticed in specimens 20 milli- 
meters in length, are now about half as long as the eye and, being dark in color in 
contrast with a light background, they are readily visible. 
Specimen 85 millimeters long. — The differences between a fish of this size and those 
that are about 45 millimeters long is not pronounced. However, at a length of 85 
millimeters the pectoral fin has attained the proportionate length of the adult and 
now reaches opposite the middle of the dorsal base. The dermal flaps at the tip of 
the lower jaw have increased in length, as shown by the single specimen of this size 
in the collection, and are nearly as long as the eye. In 20 adult specimens, ranging 
from 130 to 140 millimeters in length, these flaps are entirely missing. The size 
attained by the fish at which the maximum stage of development of the dermal 
flaps is reached can not be stated at this time, because the collection contains only 
one specimen (85 millimeters long) between sizes ranging from the young 45 milli- 
meters long to the adult 130 to 155 millimeters long. Nor is it known when they 
again disappear. The use, or significance, of these interesting structures, not present 
in the very young and again disappearing in the adult, is not understood. 
DISTRIBUTION OF YOUNG 
The numerous specimens of young Parexocoetus mesogaster in the present collec- 
tion all were taken at the surface by the Fish Hawk. Since nets suitable for taking 
the fry were not hauled on the bottom in those areas where the young were taken 
at the surface, it can not be definitely stated that the young, like the adults, are 
chiefly pelagic. It is probable, however, that this fish spends its entire life at or 
near the surface of the ocean. 
The young were all taken at stations a considerable distance offshore; that is, 
in the vicinity of Cape Lookout Lightship, the blackfish (sea bass) grounds, and in 
the Gulf Stream. Intensive collecting during the past three years (1927 to 1929) 
with 1-meter townets along the outer shores of the banks and out at sea a distance 
of about 12 to 15 miles, has yielded no specimens of this flyingfish. Neither were 
