418 



ARTHROPODA. 



FIG. 420. Daphnia pulex. 6, brood chambers with embryos; <?, brain with nauplms 

 eye; go, optic ganglion; /i, heart; o, ovary; s, shell gland. The eggs arise at fc, and 

 separate, forming in groups of four, as at e, of which one becomes the egg, while 

 the others abort (o) and form food. The egg then passes to the brood chamber. 

 1, 2, first and second antennae; 5, mandible (maxilla rudimentary and invisible); 

 5-9, lege. g, brain; go, optic ganglion; h, heart. 



