CRUSTACEA OF FRESH WATERS 171 



surviving freezing or drying. In the early part of 

 the breeding season the eggs have thin shells, and 

 they hatch after a short time. In the autumn, 

 however, thick-shelled eggs are produced, which lie 

 dormant in the mud until the following spring. It 

 has recently been discovered that species of Cyclops 

 and Canthocamptus pass through a resting stage, in 



Fig. 59 — Diaptomus ccendeus, Female, x 25. (After Schmeil.) 



which the animal surrounds itself with a cocoon-like 

 capsule of mud held together by a glutinous secretion 

 produced by glands on the surface of the body and 

 limbs. The encapsuled animals, in the cases 

 observed, lie dormant in the mud during the 

 summer, to resume active life in the colder months 

 of the year. It is very probable that they can also 

 be dried without injury, and that the *' cocoons " 



