164 
BULLETIN OF THE BUREAU OF FISHERIES 
In records of past years (fig. 64) the overlapping of fall and winter species 
shows very clearly. The winter type often appears as late as April, but disappears 
as soon as the temperature of the water rises. In 1894 and 1896 appendiciilarians 
appeared in large numbers in June. This is very unusual and may have been caused 
by an influx of Gulf Stream water. 
Swarms of Salpa democratica-mucronata Forskal blew ashore at Menemsha 
Bight in Vineyard Sound on January 11, 1901. None are recorded from surface 
collections in Great Harbor, but they may be expected at any time dm-ing that 
month after hard southwest winds. 
FISH 
Ehrenbamn states (in his excellent volmne on the "Eier und Larven von 
Fischen") that the young stages of all fish, even those belonging to the bottom 
dwellers, are usually true planktonic forms diu-ing and often after their larval 
period. 
From the standpoint of the planktonologist, fish of the Atlantic coast may be 
grouped roughly under two headings — ^those that have pelagic larvse and those that 
have not. The latter group, of which Opsanus tau (Linnteus) is a striking example, 
contains very few members and does not enter into the plankton problem. 
The first group is of great importance. A division may again be made here to 
separate those fish having pelagic eggs from those having demersal ones. No 
relationship exists between the condition of egg laying and the habits of the fish 
or between the various species of fish having these habits. Bottom-living forms, 
such as Gadus callarias and Tautoga onitis, have pelagic eggs while Clupea harengus, 
a surface dweller, has demersal ones. As a rule, most of the larger fish of this 
region belong to the group having buoyant eggs, the demersal group being composed 
of such small forms as Ammodytes, Pholis, Apeltes, Cyprinodon, Lucania, Fxmdulus, 
and Menidia. As many investigators have shown, special adaptations enable both 
types of eggs to have the best possible chance to svu-vive. 
In order to overcome the many difficulties besetting pelagic life, fish with 
buoyant eggs extrude enormous numbers of ova. These are small, translucent, and 
practically invisible against the bright sky, which forms the background. A very 
few species have pelagic eggs, which float together in a gelatinous membrane, 
often many feet in length. Such a condition is characteristic of Lophius piscatorius. 
The incubation period of pelagic eggs is comparatively short, largely governed by 
the temperature of the water. The yoimg fish hatch in a very immature con- 
dition, and these, too, are translucent except for the eyes and scattering yellow and 
black chromatophores. For several days they are quite helpless, and undoubtedly 
during this period enormous numbers are destroyed. Later they become very lively, 
darting about and feeding ravenously on copepods. It is interesting to note that 
the eggs become translucent just before spawning. During development they are 
rather opaque, and the yolk is deeply colored. 
Demersal eggs are laid in bunches on the sea bottom or attached to plants by 
fine threads. Here, again, there are special adaptations for fertilization and pro- 
tection. Contrasted with the former group, where the females outnumber the 
males, Mcintosh found that fish of this group are mostly males. This condition 
