2 66 
BRITISH ENTOMOSTRACA. 
the females are the most abundant. Their habits are 
rather difficult to observe, as they generally die soon after 
the fish upon which they live are taken out of the water. 
Pickering and Dana introduced several individuals into 
a glass of salt water, soon after the fish was caught, and 
remarked that the greater portion of them sought the 
surface, where they attached themselves to the sides of 
the glass. Many quitted the water entirely, and crept 
up the glass for an inch or two above the surface. In 
doing so, they carry a portion of water with them, confined 
under their broad carapace, the margin of which is closely 
attached to the side of the vessel, and thus are enabled 
to exist for some little time. They did not seem, however, 
to make any attempt to return to the element they had 
left, and died soon afterwards. 
When living attached to the fish, should they be 
touched or disturbed, they move with considerable ra- 
pidity, and travel over the body of their host, moving 
along with equal facility either backwards or forwards. 
By means of their natatory or branchial feet, they swim 
also with considerable rapidity, and no doubt occasionally 
change from one fish to another, as Strom had long ago 
observed. Their food does not seem to be exactly ascer- 
tained. Strom asserts that they live by sucking the blood 
from the fish, and says that he has seen that fluid flow 
into the mouth of the Caligus, and thence through the 
neck and whole body. 
As Muller justly remarks, however, with regard to 
Strom’s observations, they carry little, weight with them, 
for as he mistook the tail for the head , he must have 
misunderstood the nature of what he saw, and perhaps 
taken the genital organs for the mouth. “ I cannot 
believe,” he says, “ that they suck the fishes, but it is 
more probable, from their moving their branchial feet, as 
all the rest of the Entomostraca, that they cause the water 
to carry to their mouth the molecules floating in it, and 
the mucus from the fish.” O. Eabricius also says, that 
the species he describes nourishes itself with the mucous 
