entom6straca and phyll6poda. 263 



marked in Artemia (Fig. 188), and InBranchipus (Fig. 

 189). Eyes are usually present, and large. In some 

 forms they are elevated on stalks, thus reminding the 

 observer of the stalked eyes of the lobsters. 



The eggs of the bivalve Phyllopoda are kept within 

 a brood cavity, somewhat as in smiliarly incased Ento- 

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

 ried 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 resemblance to the adults. 



In the fresh and brackish waters of the eastern part 

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

 poda represented, and none have yet been found in 

 the ocean; while on the western plains and among the 

 Rocky Mountains they abound. These latter forms 

 are, however, not included in those referred to in the 

 following 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 

 coating give them the appearance of firmness or of 

 hardness, but they are delicate and easily injured. 

 The large Phyll6poda 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 observer may meet with in using it 

 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 

 determined by these appearances alone, and the name 

 learned by the Key, in connection with a pocket-lens. 



