COPEPODA 



(in distinction from many of the Phyllopoda). wn,, i..ur or iivc 

 two-branched swimming feet on the thorax and an abdomen with- 

 out appendages. The Copepoda are divided into two subor(ler>. 

 the Eucopepoda and the Branchiura. 



The Eucopepoda do not have compound e>es, and the Lg^s 

 develop in one or two brood pouches or ovisacs attached to the 

 abdomen. The Branchiura have two compound eyes. The females 

 do not have ovisacs, but the eggs are kud on stones or other con- 

 venient hard surfaces. The body is flattened. The KucopejKida 

 may be considered in two divisions, — Gnathosloniata. and Para,sita 

 or Siphonostomata. The Gnathostomata inckide the free-swim- 

 ming Copepoda; they have appendages about the mouth adapted 

 to mastication and the full number of body segments. The Si- 

 phonostomata are parasitic; they have the appendages alxiut the 

 mouth adapted for piercing or sucking, and generally also a re- 

 duced number of body segments. The following table shows this 

 classification : 



Branch: Arthropoda. 



Class: Crustacea. 



Subclass: Entomostraca. 

 Order: Copepoda. 



Suborder: (a) Eucopepoda. 

 Group I. Gnathostomata. 

 Group 2. Siphonostomata. 

 Suborder: (b) Branchiura. 



KEY TO NORTH AMERICAN FREE-SWIMMING COPEI*ODA 

 (GNATHOSTOMATA) 



I (104) Cephalothorax and abdomen distinctly separatL-d 



2 (76) Antennae long, commonly nearly or quite as Ioiir as the whole 



animal, and composed of 23, 24, or 25 segments. Antennae 

 of male asymmetrical, the right genicuhite and miMJilied as 

 a grasping organ. The fifth feet are uiilikc in the two sexes, 

 and in the male the right and left fifth feet arc dissimiLir. 

 Family CENXROPAcroAi 



3(8,73) Endopoditesof first swimming feet composed of one segment. . .\ 



4 (7) Endopodites of second, third, and fourth swimming feet compose<l 



of one segment. Each furcal ramus armed with three 

 large setae. Abdomen of male asymmetrical, and armed 

 on right side with a peculiar grasi)ing arrangement. 



Epischuru . 5 



