484 
BULLETIN OF THE BUREAU OF FISHERIES 
Figure 98. — Monacanthus hUpidus. 
Drawn from a specimen 1.7 millimeters 
long 
become united to form the single membranous fin now present on the median line of 
the abdomen. This membranous appendage on the abdomen will soon develop into 
a strong spine. (Fig. 99.) 
Specimens 3 millimeters long. — The body has become considerably deeper, espe- 
cially in the anterior portion of the caudal region. Posteriorly the tail remains 
slender and pointed. The snout now projects rather prominently in advance of the 
eye and is becoming slightly 
conical, while the mouth is small 
and terminal, as in the adult. 
The dorsal spine is high and 
prominent, being equal to about 
two-thirds the depth of the 
body, and from its anterior and 
posterior margins project a 
few spiny barbs, variable in size. 
The ventral spine has become 
strong and rigid. The soft dor- 
sal, caudal, and anal are becoming slightly developed with traces of rays, and 
small prickles are beginning to appear on the body covering. Dark pigment is pres- 
ent on the head and generally extends on the back. The ventral periphera, including 
the ventral spine, usually is slightly pigmented with black. Similar pigmentation 
occurs on the side above and behind the abdomen. (Fig. 100.) 
Specimens 5 millimeters long. — The body is shaped very much as in the adult. 
The tail now is moderately deep and it supports a well-developed, rounded caudal 
fin. The soft dorsal and 
anal, too, are fairly well 
developed. The barbs on 
the dorsal spine have in- 
creased in number and size, 
and the skin is now quite 
generally beset with prickles. 
Pigmentation in preserved 
specimens consists princi- 
pally of dark dots scattered 
over the body. 
Specimens 8 millimeters 
long . - — Specimens 8 milli- 
meters long are very similar 
to the adults in shape. The 
snout, however, remains much shorter and blunter. The dorsal spine still has large 
barbs on both the anterior and posterior margins; the ventral spine is very prickly 
and largely free, the membranous flap which later ties it to the abdomen being 
mostly undeveloped. The other fins are all well developed and shaped as in the 
adult. Pigmentation consists principally of brownish spots with dark centers, 
present everywhere on the body, exclusive of an area behind the eye and around 
the gill opening. (Fig. 101.) 
Specimens 15 millimeters long. — In shape and form the body is now identical 
with the adult, except that the snout remains too blunt and does not project as 
Figure 99. — Monacanthus hispidus. Drawn from a specimen 2 millimeters long 
