150 



SYSTEMATIC ZOOLOGY 



Order i. Phyllopoda 



The Phyllopoda (Gr. <$>i)\\ov, leaf, and Trow, foot) are mostly 

 fresh-water Entomostraca ; a few live in brackish and in salt 

 water. The body is distinctly segmented and exhibits three 

 regions : the head of four or five fused segments, the thorax 

 provided with several pairs of appendages, flattened and leaf- 

 like, and the abdomen, or posterior region, which is without 



FIG. 141. A pus cancriformis. Dorsal aspect ; 

 enlarged, aid, abdomen; a./ caudal styles ; 



d.o, dorsal organ; /•', paire . median 



eye; shgl, shell-gland; th /'./, endites of first 

 thoracic foot. (From Parker and Hasv 

 Text-book.) 



FIG. 142. Apusglacialis. Ventra 

 aid./, abdominal feet; ant.i, antennule; 

 ant. 2, antenna; Ibr, labrum ; md, man- 

 dible; mx, first maxilla 

 oviduct, ib-frontal plate; sh.gl, 



gland; th./, thoracic feet; th./.l, 

 first thoracic foot. (After Bernard, from 

 Parker and Haswell's Manual.) 



appendages. Most of the Phyllopoda are almost microscopic in 

 size, but some are several centimeters long. They present the 

 greatest diversity in form. Some, like Apus( Figs. 141 and 142 ), 

 are flattened dorsoventrally and have a large cephalic carapace 

 which extends backward over the whole thoracic region. The 

 majority have the body compressed laterally, sometimes without 



