578 
BULLETIN OF THE BUREAU OF FISHERIES 
of August. It may be concluded, therefore, that the spawning period extends from 
May to August. 
The eggs were seen first on August 25, 1927, when a female held in a battery 
jar spawned. Since no male was at hand the eggs could not be fertilized. Several 
“nests”, each containing many eggs, were taken from May 31 to June 27, 1932. 
From this material it was possible to study the embryology in detail. 
This blenny does not make a nest in the true sense of the word. However, it 
uses empty oyster shells (possibly also clam and scallop shells) with the hinge in- 
tact, from which the oysters probably have not been removed very long and which 
are still clean and white within. Therein the eggs are deposited, and they become 
firmly attached by means of an adhesive disk. In several instances, nearly the 
entire inner surface of both valves of the oyster shell was covered with eggs. Occa- 
sionally only a part of each valve was occupied by the eggs. It seems probable that 
in these last mentioned instances the nests were not completed, and that more 
eggs would have been deposited. Nests were found only on a natural oyster reef at 
the west end of Pivers Island, at or near the usual low tide line. 
It is evident from the difference in the development of the eggs in a nest that 
they are not all spawned at the same time. The difference in development may 
range from an early cleavage stage to an advanced embryonic stage, suggesting that 
the eggs are laid over a period of several days. In general, the eggs near the hinge of 
the oyster shell are furtherest advanced, whereas those most distant from the hinge 
of each valve show the least development. 
The eggs are in a single layer in the nest, not always in definite rows, and are well 
separated by the adhesive disks which have a greater diameter than the eggs. It is 
estimated that some of the larger nests found contained as many as 3,750 eggs. The 
eggs are so firmly attached that they can be removed without injury only by cutting 
the adhesive disk close to the oyster shell with a sharp instrument. 
It is not known whether all the eggs in one nest are the product of one female, 
although this seems quite possible since all the eggs within an ovary evidentally do 
not mature at one time, as already stated. It is possible, therefore, that a female 
may go to the same nest several days in succession to spawn . 7 
The eggs probably always are guarded by a male. The foregoing statement is 
made notwithstanding the fact that a few nests were found with which no males were 
seen. On the other hand, a fish was seen to escape from a nest in a few instances, 
and several nests were taken with the male within the valves of the oyster shell con- 
stituting the nest. It is assumed in those instances when no males were seen that 
they escaped unnoticed. 
The male stays within the oyster shell in taking care of the eggs. In case the 
shell is shorter than the fish it bends the tail forward to get within the shell, for it 
allows only the snout and eyes to protrude. A decided difference in the temperament 
of different males was noticed. It already has been shown that some males fled when 
someone approached. Others stayed with the nest and allowed themselves to be 
picked up (by hand) with the oyster shell containing the eggs. Only one male, upon 
being transferred from its native habitat to the aquarium, reoccnpied his nest almost 
immediately, although others, after being in confinement for some time would even 
occupy empty shells. In a few instances males failed to return to their nests in 
7 Guitel (1893) has reported that among specimens of Blennius montagui=B. galerita, from the coasts of France, kept in a tank 
made of a small boat, in which their natural habitat was reproduced as nearly as possible, several females laid eggs in one nest situ- 
ated on the under side of an overhanging stone. The eggs were all fertilized and guarded by the same male. It cannot be stated 
of course, that this procedure would obtain in nature. 
