HARRIS : CRAYFISHES GENUS CAMBARUS. 169 



In C. virilis eggs are laid in the spring, none being found on 

 females taken during the winter. The ovarian eggs of speci- 

 mens taken in January seem, so far as may be seen from a 

 rough examination, to be fully developed. 



In connection with a discussion of the breeding habits, it may 

 be well to bring together a few observations which have been 

 made on the habits of the young after leaving the parent. 



Abbott ('73) says, in speaking of C. affinis, C. acutus, and C. 

 bartonii : "The young Cam6ari, in September, seem to be fully 

 as active as the adults, but do not frequent any given class of 

 localities, as they wander about the beds of streams, creeping 

 forward in a slow, awkward manner, and swimming backwards, 

 when disturbed, with wonderful rapidity." 



Williamson ('01) notes the presence of forty-seven young, va- 

 rying from three-fourths to one and one-eighth inches in length, 

 in a burrow with an adult female of C. caroliiius on September 

 24. Young animals about one inch in length were taken in the 

 small pool of water where the adults of C. simulans reported by 

 Harris ('02) were taken in burrows. 



Harris ('00) notes the occurrence of numbers of young cray- 

 fish, apparently C. f/racilis, in stagnant ponds, where he had 

 noticed young in the spring of the year, about October 20 to 

 November 20, appearing in great numbers at about the time the 

 adults of C. immunis disappeared. They were about three- 

 fourths to seven-eighths of an inch in length. About the 1st of 

 March of the next year they appeared before the adults, and al- 

 though a few days later the pond froze over they were still to 

 be found apparently as plentiful as ever beneath a layer of ice 

 an inch thick. By the 1st of May they had attained a length 

 of from one to one and one-half inches, while May 9 many 

 small animals about five-eighths of an inch in length were ob- 

 served. These were probably the young of C. gracilis, which 

 are carried by the female as late as March 27. It seems, then, 

 that young and adult C. gracilis appear in the ponds early in 

 the spring and that the young again appear in the fall after 

 the other species have gone to their burrows. 



Abbott ('84) has called attention to the neatness of the cliim- 

 neys constructed by the small individuals of C. diogenes. I have 

 noticed the same thing in C. gracilis and C. immunis {?). As 

 he suggests, it may have some significance. 



