368 



ARTHROPODA 



is not so well developed, and in some cases is represented by two 

 bunches of bristles. 



FIG. 384. Evadne (orig.), showing the brood pouch filled with eggs and young. 

 a 2 , second antenna; ao, adhesive organ; b, brain;/, furca; h, heart; i, intestine; I, liver; 

 s, shell gland. 



FIG. 385. Dioptonnts castor, b, ventral nerve cord; g, brain with nauplius eye; /;, 

 heart, beneath it the ovary and digestive tract; sf>, spermatophores ; i, 2, first and 

 second antenna-; 3, mandibles; 4, maxilla;; 5, maxilliped; 6-10, swimming feet. 



The first pair of antennae in the males may be hooked near the base for 

 clasping; the second are sometimes biramous (fig. 374, //). The mandible 

 (fig. 374, 777, V) is instructive, since a study of several species shows that it is 

 derived from a schizopodal condition and that the first basal joint alone is used 

 for chewing, the rest being reduced to a palpus of varying development. Both 



