THE CRAYFISH AND ARTHROPODS IN GENERAL 



213 



sterna of the segments bearing the fourth and fifth pairs of 

 walking legs. 



EGG-LAYING (159, 160). The eggs are laid at night during 

 the month of April. First the ventral side of the abdomen is 

 thoroughly cleaned of all dirt by the hooks and comb-like bristles 

 near the end of the fifth pair of walking legs. A clear slime or 

 glair is secreted by cement glands situated chiefly on the basal 

 parts of the uropods, and on the endopodites of the other abdomi- 

 nal appendages. This milky glair gradually covers the swim- 

 merets. The female then lies on her back, and an apron-like 

 film of glair is constructed between the ends of the uropods and 

 telson, and the bases of the second pair of walking legs (Fig. no). 



FIG. no. Female crayfish lying on back laying eggs. (From Andrews ir 



Am. Nat.} 



The eggs emerge from the openings of the oviducts in the bases 

 of the third pair of walking legs, flow posteriorly, and become 

 attached to the hairs on the swimmerets by strings of a substance 



