452 
BULLETIN OF THE BUREAU OF FISHERIES 
ever, the scales generally are lost and they are not shown on the accompanying 
drawing. (Fig. 67.) 
Specimens 55 millimeters long.— The, shape and form of the adult is now fully 
developed. The dermal tentacles, inserted at the tip of the lower jaw, are com- 
paratively large, reaching slightly beyond the eye in the single specimen of this size 
at hand. The limited number of specimens of this and larger sizes in the collection 
indicates that the maximum stage of development is reached at this length. Pig- 
mentation on the body still consists principally of the dark rings described in speci- 
mens 35 millimeters long. The pectoral fin now has two dark spots on the outer 
rays, whereas the inner rays are dark, except at the base and a dark bar crosses the 
middle of the fin and extends to the tip of the longest rays. Nichols and Breder 
(1928, p. 448) published a color plate of a fish 65 millimeters in standard length. 
While we have no specimen of exactly that size, our smaller, as well as larger ones, 
have much more dark color on the pectoral fins than shown in the color plate. The 
color of the ventrals is similar, but none of our specimens have dark spots or bars on 
the caudal fin, as shown in the color plate mentioned. 
Specimens 90 millimeters and more in length.- — A specimen 90 millimeters in length 
has rather short dermal appendages at the tip of the lower jaw which reach only a 
little past the anterior margin of the eye and are only about two-thirds as long as the 
eye.* In color the bod}^ is plain, light brown with only a trace of the dark rings, 
described for smaller fish, remaining on the chest and abdomen. A specimen only 
slightly larger (95 millimeters) has no trace of dermal tentacles on the lower jaw. 
The ventral fins do not quite reach the base of the caudal and have attained the pro- 
portions of those of the adult. In color it is more uniform and without traces of dark 
bars or rings. The pectorals and ventrals, however, are very largely black. Two 
adult fish, respectively 135 and 140 millimeters in length, have no trace of dermal 
appendages on the lower jaw. Insufficient specimens are at hand to draw conclu- 
sions. However, the indications are that in this species as in Parexoccetus mesogaster 
(see p. 448) these dermal tentacles, which are not present in the very young, again are 
missing in the adult. No specimens with branched barbels, such as is figured by 
Fowler (1906, p. 288), are included in the present collection. Nor does the coloration 
of our specimens agree with Fowler’s illustration. The dark markings on the pectorals 
probably vary. However, the ventral fins in all of our specimens of 35 millimeters 
and upward in length are blotched with black and in a specimen 90 millimeters long 
the characteristic pearly gray spot of the adult already is developed. Fowler’s 
illustration shows the ventrals unmarked. 
Very young Parexoccetus mesogaster and Cypselurus jurcatus may be distinguished 
from each other by the generally lighter color and the much more profuse spotting 
with black chromatophores of the body in the latter. At a length of 10 millimeters 
the ventral fins in C. jurcatus already are proportionately longer than in P. mesogaster 
and as the fish increase in size this difference becomes more pronounced. Due to the 
early development of the fins, the species can be separated even at a small size (5 to 
10 millimeters) by the enumeration of the dorsal and anal rays, P. mesogaster usually 
having 11 dorsal and 13 anal rays, whereas C. jurcatus usually has 14 dorsal and 10 
anal rays. 
DISTRIBUTION OF YOUNG 
All of the specimens in the present collection from the vicinity of Beaufort, both 
adults and young, were caught at the surface. No nets suitable for taking the young 
on the bottom were used by the Fish Hawk which collected all the locally caught 
