244 MICROSCOPY FOR BEGINNERS. 



Brancliipus (Fig. 170). Eyes are usually present, and 

 large. In some forms they are elevated on stalks, thus 

 reminding the observer of the stalked eyes of lobsters. 



The eggs of the bivalve Phyllopoda are kept within 

 a brood cavity, somewhat as in similarly incased Ento- 

 mostraca, while in the shell-less forms they are carried 

 about in a bottle-shaped sack at the end of the body, 

 near the origin of the long, narrow, tail-like portion. In 

 both kinds the young bear scarcely the remotest resem- 

 blance to the adults. 



In the fresh and brackish waters of the eastern part 

 of the country there are but few genera of the Phyl- 

 lopoda represented, and none have yet been found in the 

 ocean ; while on the western plains and among the 

 Kocky Mountains they abound. These latter forms are, 

 however, not included in those referred to in the fol- 

 lowing list. 



All these little crustaceans should be examined in a 

 deep cell, to prevent the weight of the cover-glass from 

 crushing their bodies. The shells and the shelly coat- 

 ing give them the appearance of hardness, but they are 

 delicate and easily injured. The large Phyllopoda will 

 need an especially deep and extensive cell. 



The following Key will lead to the common genera 

 of both divisions of these attractive animals. The only 

 trouble the beginner may meet with in using at will 

 probably be in determining whether the specimen is a 

 Phyllopod or an Entomostracan ; but as the former are 

 large, and swim on the back, they may usually be deter- 



