/. CRUSTACEA: COPEPODA. 



421 



or complete, of a circulatory system, and the absence of gills are 

 all evidences against the view which woul J consider them primitive. 



Order I. Eucopepoda. 



The forms to which the foregoing description will apply are the Euco- 

 pepoda, and include many species, which often occur in enormous numbers 

 in both fresh and salt water, forming the larger proportion of the plank- 

 ton. They thus furnish the most important food supply not only for fishes 



Fig, 423. 



Fig, 424. 



Fig. 433.— Female Lerncnocera e^ocina, {From Lang, after Claus.) A, armlike proc- 

 esses o( anterior end; d, digestive tract; «s, egg-aacs; od, oviduct; (i-(,, rudi- 

 mentary thoracic appendages. 



Fig. i2i.—Argulus foliaceus. (From Ludwig-Leunis.) a, sting; a', antenna ; f), 

 mouth; c, intestine with liver; rf, abdomen; pni\ ^/ni^, iirst and second maxiili- 

 peds ; i.»^-p*, biramous feet of thorax. 



but for those giants among mammals, the baleen whales. Getochilus sep- 

 tentrionalis occurs at times in such myriads that the sea for long distances 

 is colored red. 



The CyclopiDjE, with no heart and paired egg sacs, are fresh-water 

 forms; Cyclops * (fig. 7). Calanid.e, fresh water and marine; heart pres- 

 ent, single egg-sac. Diaptomus,* fresh water (fig. 423); Cetochilus* Pon- 

 tilla* marine. HAEPACTlDiE, creeping forms, mostly marine; Cantho- 

 camptus* fresh water. The CoRVCyEiD^, which are half parasitic and 

 incliulo the wonderfully iridescent Sapphirina * (upon pelagic animals, as 



