ENTOMOSTBACA AND PHYLLOPODA. 243 



of more or less fine comminution ; for, nearly without 

 prehensile organs, these animals, by means of a valvular 

 or, at most, ladle-like labrum, dip from the current of 

 water kept flowing by the constant motion of the bran- 

 chial feet, such fragments as the snail and scavenger- 

 fish have disdained : bits of decaying Algae, or the 

 broken fragments of a disintegrated mosquito, all alike 

 acceptable and unhesitatingly assimilated. The amount 

 of such material that they will dispose of in a short period 

 of time is truly astonishing." 



When the shallow ponds are dried by the summer 

 heat, the Entomostracans bury themselves in the mud, 

 and there remain quiescent, but alive, so long as any 

 moisture is present. When the mud is completely 

 dried they die, but the eggs have the ability to endure 

 heat and dryness without injury, and to develop and 

 mature as the pools again become filled by the rain, or 

 by the melting snow of early spring. 



The Phyllopoda may also often be recognized without 

 a microscopical examination, by their large size and al- 

 most universal habit of swimming on the back. Bran- 

 ckipus, sometimes called the fairy shrimp, and Artemia, 

 or the brine shrimp, are nearly an inch in length. 



As in the Entomostraca, their bodies may be incased 

 in a bivalve shell or not. The broad, flattened feet are 

 numerous, but the branchial or breathing-plates already 

 referred to may be small and inconspicuous, and there- 

 fore difficult to be observed by the beginner. They are 

 especially well-marked in Artemia (Fig. 169), and in 



