594 



ZOOLOGY 



SECT. 



In most of the the Branchiopoda, Ostracoda, Copepoda, and 

 Cirripedia, respiration takes place by the general surface of the body, 

 and the only respiratory organs are specially modified parts of the 

 appendages. In the stalked Barnacles, however, there are delicate 



FIG. 471. Orchestia cavimana, male, a, eye ; a\, antennule ; 02, antenna ; aoa, anterior 

 aorta ; aop, posterior aorta ; bm, ventral nerve-cord ; br, gills ; C+ T, cephalothorax ; de, vas 

 deferens ; ed, rectum ; g, brain ; h, heart ; hd, intestine ; kf, maxillipede ; I, digestive glands ; 

 ce, gullet ; p 1 p 7, abdominal segments ; sm, ' ' stomach " ; ud, intestinal caecum ; vs. vesicula 

 seminalis; t, testis ; II VIII, free thoracic segments. (From Lang's Comparative Anatomy, 

 after Nebesky.) 



processes attached to the feet, which are supposed to be rudiment- 

 ary gills. Amongst the Malacostraca also, the Phyllocarida, many 

 Mysidacea, and the Cumacea have no specialised respiratory organs, 

 but the Euphausiacea possess tufted podobranchia3 (Fig. 472) quite 



