I. CRUSTACEA: COFEPODA. 



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degenerate (figs. G, 423) as to be recognized even as arthropods 

 only by a knowledge of the development. The sixteen somites oi 

 the Ijody are nearly eqnally divided among the three regions — 



Fig. ^\.—'Ev(uUu: (orig.), wljowing the brood pouch lllled with eggs and young, a^, 

 second antenna; an, adhesive organ; h^ brain; /, furca; ?i, heart; /, intestine; /, 

 liver; s, shell gland. 



Fio. 422.— I>/*(pto?)iws crtstor. h, ventral nerve cord; g, brain with nauplius eye; h, 

 heart, beneath it the ovary and digestive tract; sp, spermatophores ; 1, 'J, flrst and 

 second antennae; J, mandibles; i, maxillte; .5, maxilliped; o-io, swimming feet. 



head (0), thorax (5), and abdomen (.5) — of the animal. (In Cyclops 

 the first thoracic segment is fused with the head, the first two 

 abdominal segments are fused — fig. 7.) The terminal abdominal 



