478 
BULLETIN OF THE BUREAU OF FISHERIES 
filaments increase in number with age, some of them becoming bifid, and they persist 
until a length of at least 10 millimeters is attained. The high number of vertebrae 
(about 43 to 47), as shown by the muscular rings, is helpful in separating the tongue- 
fish from the other flatfishes of the vicinity of Beaufort. 
Specimens 3.0 millimeters long. — The body has increased in depth at this size. 
The forehead is scarcely as prominent as in a 2-millimeter specimen, the chin is less 
strongly angled, but the abdomen 
is larger and protrudes even more 
strongly. The intestine remains vis- 
ible through the abdominal walls, as 
in smaller specimens. The mouth 
remains close to the eye and strongly 
oblique. Instead of 2 filaments at 
the occiput, as in the smaller speci- 
mens, 3 or 4 are now present. In- 
dications of fin rays have appeared 
within the fin fold on the distal part 
of the tail, and a pectoral fin is be- 
coming visible. The elongated dark 
spots on the back, described in the 2.0-millimeter specimens, are more evident and 
more elongated, and in some specimens an indication of a fine dark line between them 
is present. A finely dotted line is now plainly evident along the ventral edge of the 
caudal portion of the body. The body remains entirely symmetrical and the slight 
pigmentation just described is identical on both sides of the fish. (Fig. 92.) 
Specimens 5.0 millimeters long. — The caudal portion of the body is much deeper 
than it is in a 3 .0-millimeter specimen , but the anterior portion has decreased in depth and 
the abdomen protrudes much less prominently. The forehead is now much lower; the 
eye is proportionately smaller, 
and the mouth is much farther 
removed from it. The course 
of the alimentary canal remains 
only faintly visible through the 
abdominal walls. The margin 
of the opercle is becoming visible, 
branchiostegals are evident, and 
the maxillary and premaxillary 
are well outlined. The filaments 
on the head have increased still 
further in number, four to seven 
now being present. They are 
unequal in length and in some 
specimens the longest ones are 
bifid. Fin rays of the dorsal, caudal, and anal fins are well developed, and the pectoral 
fin is distinct. Pigmentation differs only slightly from that of a 3. 0-millimeter spec- 
imen. The notochord remains visible throughout as a pale streak. Symmetry remains 
perfect in all external characters, except that the vent is situated to the right side of 
the anterior rays of the anal fin. (Fig. 93.) 
Specimens 7.0 millimeters long. — Development has proceeded regularly since a 
length of 5.0 millimeters was attained but the changes are not pronounced. The 
