DEVELOPMENT AND LIFE HISTORY OF SOME TELEOSTS 
579 
nature after being disturbed. One male transferred to the aquarium devoured the 
eggs, instead of taking care of them. The single male which reoccupied his nest in 
the aquarium not only stayed in the oyster shell until the eggs were hatched (not- 
withstanding frequent disturbances during the incubation period for removing eggs 
for study), but also for several weeks afterwards or until removed from the tank. 
During the incubation period, as well as afterwards, he came out only to feed on bits 
of oyster and fish that were supplied, and even retreated between bites. 
The male undoubtedly drives away intruders, for it was noticed that the eggs 
in nests deserted by the parent fish were destroyed very soon. The chief enemy 
noticed was the flat mud crab, Eurypanopeus depressus (Smith). 8 Specimens of this 
crab were taken with three deserted nests. The male, however, appears to have 
another function, namely that of keeping the eggs clean and in healthy condition. 
Just how this is accomplished is not evident. It was not noticed that he fanned the 
eggs especially, for he seemed to lie quietly within the oyster shell. 9 Yet, the eggs 
in a nest cared for by a male, and held in a tank with running water almost all hatched, 
whereas the eggs treated identically, but without a male attendant all died in ad- 
vanced embyronic stages. A very small number of eggs in one deserted nest was 
hatched by providing special treatment. That is, in addition to keeping the nest in a 
tank with running water, the eggs were washed vigorously once or twice each day by 
playing a jet of water directly on the eggs, and by rushing the nest through water 
rapidly. A few eggs removed from a nest were hatched in standing water (changed 
twice daily) in a glass bov/1. Eggs in deserted nests in tanks became infested with 
hydroids and copepods, which caused death before hatching. No infestations were 
noticed in eggs guarded by the male fish. 
Spawning apparently takes place early in the morning. This conclusion is 
arrived at from the fact that eggs in early cell division stages were present only in 
nests taken before 9 o’clock in the morning. All eggs collected even as late as 11 
o’clock in the morning already had passed the early cell division stages and those taken 
during the afternoon had progressed correspondingly further in development. 
DESCRIPTIONS OF THE EGGS AND YOUNG 
Description of the eggs . — The eggs of Hypsoblennius hentz are slightly flattened 
next to the adhesive disk or foot which attaches them to oyster shells, as already 
explained. The foot and the slight depression in the contour of the egg at the place of 
attachment are shown in only two of the accompanying drawings (figs. 77 and 83). 
The greater axis in 11 eggs measured varied from 0.72 to 0.8 mm, the average being 
0.769 mm. The smaller axis which is difficult to measure accurately because the 
opaque foot obscures the outline of the egg, varied in four specimens from about 
0.64 to 0.68 mm. 
The eggs, as seen with the unaided eye, if still in rather early developmental stages, 
are pinkish in color. Under magnification it becomes evident that the color is within 
the yolk and in the form of spherical or more or less elongate bodies. The longest 
diameter of the latter apparently is always perpendicular to the plane to which the egg 
adheres. These bodies, as seen under magnification, are violet to old rose in color. 
They are variable in size within the same egg, as well as in shape and number in dif- 
ferent eggs. They lie at various depths within the yolk, and therefore it is necessary 
to refocus the microscope to see all of them. The variation in number in different 
8 The writer is indebted to Dr. Mary J. Rathbun of the U. S. National Museum for the identification. 
• Guitel (1893) stated that the male of Blennius montagui=B. galerita, a European species, does fan the eggs and that he will 
remove with his mouth any foreign object which may enter the nest. 
