84 THE GOLDFISH AND ITS CULTURE. 
in length. It crawls about upon the bottom of the ponds and over 
the water plants, searching for food, part of which consists of fish 
eggs, to which they are very destructive, devouring them wherever 
found. 
Another voracious enemy of the crustacean tribe is 
THE WATER FLEA 
(Gamarus pulex.) 
or Flea Crab, Buck Crab, etc. This lively little creature is closely 
related to the shrimp found in the ocean. It furrows through the 
THE WATER FLEA (enlarged). THE WATER ASELL (enlarged). 
water in any direction lying on its side, because its back is naturally 
bent. (See illustration.) In all stages of its growth it feeds upon 
the fish eggs, but in turn, furnishes an excellent food for young fish. 
THE BOAT FLY 
(Notonecta glauca, ) 
or ‘‘ Shoemaker,” 
as it is commonly called, is a most voracious 
insect. The body is long, contracted posteriorly, convex abcve 
and flat below, having hair at the sides and extremities, which, 
when spread out, supports the insect upon the water. The 
head is large and presents a large eye upon. each side, giving 
the possessor the power of vision in all directions. The color 
of the body is a greenish grey, the wings are white, of the legs, 
