590 
BULLETIN OF THE BUREAU OF FISHERIES 
The common habitat of this blenny locally is among marine growths attached to 
wharf and bridge piling and to rocks of breakwaters. The ripe fish used in the present 
investigations were secured from the marine growths (principally asc.idians) attached 
to the wooden piling of a railroad bridge near the laboratory. The fish were caught 
with a scrape net, that is, a dip net with a flattened side, provided with a blunt cutting 
edge. With such a net the marine growths, in part, may be scraped from the piling 
and frequently a blenny is contained among them. Collecting is most conveniently 
and efficiently done on low tide. During July and August 1930, one man could catch 
from two to four dozen fish with a scrape net on the low stages of a single tide. 
Hypleurochilus geminatus is very hardy and it lives well in an aquarium. There- 
fore, if captured specimens were not quite ripe, they could be retained several days until 
their sexual products matured. 
This species occupies a habitat which is almost identical with that of the adult 
sheepshead ( Archosargus probatocephalus ) , the gamest of the locally represented salt 
water fishes. Both species feed on attached marine growths and on free swimming 
forms (principally crustaceans) which also frequent these marine growths. However, 
Figure 90 .— Hypleurochilus geminatus. From adult male 55 mm long. Note plicate membranous bulbs attached to anal spines, 
covering the anterior one almost completely. 
the competition probably is not great, as the blenny requires much smaller bits of food 
than the sheepshead. And young sheepsheads do not enter into the competition, 
because they have an entirely different habitat. (See p. 532.) 
Hypleurochilus probably is preyed upon to a limited extent by predatory fishes, 
but its habitat is very restricted, as already shown, and of such a nature that it is not 
visited by many species. Neither is this blenny abundant enough to be of much im- 
portance as a forage fish. Therefore, its economic value locally must be very slight. 
SPAWNING 
The presence of eggs of several different sizes within the ovary at one time, as 
will be pointed out subsequently, suggests a long spawning season. That the period 
of reproduction is a long one is substantiated by the presence of small fry, under 5.0 
mm in length, in the tow from spring to autumn, or to be exact, from May 11 (1929) 
to October 5 (1927). Such small young were common from the last half of May, 
through June, July, and August. In September they became less numerous. It 
seems evident, therefore, that the spawning period extends from May to September, 
