278 AQUATIC MICROSCOPY FOR BEGINNERS. 



The body of the female is as large and as stout as 

 that of the male. The egg-sack is noticeable near 

 the point of union between the posterior narrow por- 

 tion of the body and the broader front. 



It is a peculiar fact that the Branchipus is killed by 

 even the heat of early summer or of late spring. Dr. 

 A. S. Packard, describing -a visit to a pond where these 

 creatures had been found on May 2d, but from which 

 they had all disappeared by May 13th, says "It seems 

 from this quite evident that the animal probably dies 

 off at the approach of warm weather, and does not re- 

 appear until after cool weather sets in late in the 

 autumn, being represented in the summer by the eggs 

 alone; and thus the appearance and disappearance of 

 this Phyllopod is apparently determined mainly by the 

 temperature." 



A vessel full of water in which Branchipus is floating 

 on its back is a strangely beautiful and interesting 

 sight. The pale reddish or flesh-colored bodies rising 

 and falling in long curves, with their numerous broad 

 feet waving together rhythmically, make a living 

 picture long to be pleasantly remembered. 



"Those readers who desire to pursue the subject, es- 

 pecially in respect to the anatomy and development of 

 these crustaceans, are referred to Prof. C. L. Herrick's 

 "Crustacea of Minnesota," published in the twelfth an- 

 nual report of the State Geologist, and to Prof. A. S. 

 Packard's "Monograph of the Phyllopod Crustacea of 

 North America, " issued in the twelfth annual ■ report 

 of the United States Geological and Geographical Sur- 

 vey of the Territories, Dr. F. V. Hayden in charge. 



