THE BREEDING HABITS OF ANIMALS 



199 



with the eggs does not, however, necessarily imply incubation. For 

 example the common skink is a "cold blooded" animal which remains 

 with the eggs (Fig. 152). Its temperature is so nearly that of the sur- 

 rounding air that the development of the eggs can scarcely be affected by 

 the presence of the parent. Some other species apparently incubate the 

 eggs to a small extent. The python, for example, coils about its eggs, 

 and as the temperature within its coils is a few degrees above that of the 



Fig. 151. — Nost of the Australian brush turkey, consisting of litter in which the eggs 

 are buiied to be hatched by the heat of the decomposing vegetable detiris. The nest is the 

 heap of debris in the lower half of the photograph. The nests are commonly about six feet 

 high and ten or twelve feet in diameter and constructed for the use of one pair of birds, but 

 much larger ones are found which are said to be used by several breeding pairs. (Photo 

 by E. R. Sanborn, loaned by the New York Zoological Society.) 



surrounding atmosphere, development is thereby probably somewhat 

 accelerated. The habit of carrying the eggs attached to the body is 

 found in several groups, both among nest-building forms and others that 

 build no nests. Thus, the female crayfish carries her eggs attached to the 

 swimmerets under her al)domen, where she waves them back and forth. 

 The movement of the eggs increases aeration, which is perhaps necessary. 

 Freshwater mussels keep their eggs in the chambers of the gills of the 



