356 



THE AMERICAN NATURALIST 



[Vol. XL 



Summary 



The egg-laying habits of Camharus affinis are closely similar 

 to those of Astacus, as far as the latter have been described. 



In Cambarus there are four periods of activity: cleansing, 

 glairing, extrusion, turning. 



The transportation of the eggs from the oviducts to the abdom- 

 inal appendages is accomplished by gravity when the female 

 places herself in special positions. 



The activities of the female include a prolonged use of special 

 tools to cleanse the surfaces later covered by the secretions of the 

 "cement glands," a long continued maximum contraction of the 

 abdomen, a habit of lying supine and externally inert during 

 oviposition, and a long rhythmic alternation of poses associated 

 with the fastening of the eggs to the abdominal appendages. After 

 this follow the weeks of aeration and care of the eggs till they 

 hatch. 



While the ultimate analysis of the factors concerned in fastening 

 the eggs to the abdominal hairs awaits future investigations the 

 secretion of the "cement glands" seems of chief importance 

 though local activities of the egg may possibly play a part. 



