437 
Teleosts ditfer very much in the nature of their food and in their manner of 
t securing it. Some, like the Catfish, Sturgeon and Suckers, are bottom feeders, 
and such are often furnished with protractile lips, the better to secure the mol- 
luses, werms, aquatic insect-larve or fish-spawn on which they live. Others, 
like the Whitefish, are dependent on the crustacean life with which our fresh waters 
swarm, (fig. 9), the young living on the minute Lntomostraca, the adult on the 
y 
Fia. 9. 
a 
ey 
4 
Branchipus vernalis, 
swimming on its back. x 3. 
Daphnia pulex. x 18, Cypris candida. x 16. Cyclops sp. oe 
larger shrimp-like forms. Others again, more agile, leap to secure the insects on 
which they f-el, while many are carnivorvus, feeding on other smaller species of 
fish. Unquestionably the microseypic life of the fresh waters is the prime source 
of much of the food of our fresh water fishes, and most comprehensive investi- 
gations are therefore being carried on in regard to the life of the larger bodies of 
fresh water in Europe with the object of ascertaining the conditions which 
appear favourable t» the abundance of food-material of this character, and the 
species which appear to contribute most to the sustenance of the fish. 
As the smaller species of fish serve as food for the larger rapacious forms, 
which may thus be resarded as inimicu to them, so also the various fish-eating 
birds und reptiles may be regarde| as enemies of the class. There are, however, 
some more insidious enemies which are deserving of mention—the various fish- 
eatin insects, and the various parasites, animal and vegetal, which afflict fish. 
Amongst the former are specially to be noted the larger water-beetles, Dytiseus 
and Aciliws, which may completely devour small fish by the aid of their rapa- 
cious jaws; the larger and smaller water-bugs and water-boatmen, belostoma, 
Notonectu and Runatra, which attack fish by grasping them with their power- 
ful front legs and then sting them and suck their blood by their sucking 
‘proboscis. 
