bo 
26 College of Forestry 
shortly after escaping from the egg, will seize and devour 
one of these mollusks with as much ease as if schooled in the 
process a long time.” 
Cooke (1895, p. 59) cites a case of a Dytiscus in an 
aquarium which killed and devoured seven Lymnea stagnalis 
in the course of an afternoon. These beetles also ate 
Lymnea peregra, but seemed to prefer stagnalis, for when 
equal quantities of both species were placed in the aquarium, 
they chose the later species first (Baker, 1911, p. 44). It 
is probable that many of the large aquatic beetles, as well 
as their larvee, prey upon fresh-water snails. 
2. CRAWFISHUES AS ENEMIES OF MOLLUSKS. 
Crawfishes are described by most authors as omnivozous 
in their food habits, eating both plant and animal material 
as well as carrion. Forbes in his food table (1914, plate 1) 
indicates that they feed upon the Mollusca but no specific 
records of their use in the native state have been seen. Ort- 
mann (1906, p. 495) states that ‘‘any vegetable or animal 
matter, either fresh, or decaying, serves as food for craw- 
fishes, and although some species may prefer certain classes 
of food on acount of taste or necessity, they all take readily 
to any kind, as is seen by the fact that in captivity they eat 
everything that is offered to them without discrimination. 
If nothing is given, they eat one another.” In captivity 
crawfishes are fed a variety of food material. Andrews 
(1906, p. 297) states that ‘ In the spring they generally take 
food eagerly; eggs, meat, worms, potato, bread, crayfish 
flesh, mollusks, Chara and other aquatic water plants and 
algw, in fact most kinds of soft organic matter will often 
be consumed.” Chidester (1908, p. 712) states that ‘“ Raw 
and cooked meat of all kinds, worms, dead fish, pieces of 
clam, moulting crawfish, and dead crawfish were eaten by the 
crawtish in confinement.” It is probable that this group of 
Crustacea eats largely of mollusks, clams and snails. Studies 
of stomach contents would be of great value in solving this 
problem. ; 
