23 



h. Dorsum of armor marked off into polygonal areas, (fig. 35, 36). 



Anuraea. 



hli. Dorsum of armor with longitudinal furrows or striations (fig. 



33. 34), Noiholca. 



gg. Anterior margin of armor without spines. Anuneopsis. 



CRUSTACEA.=l= 



The following table includes the genera of only the free swimming, fresh 

 water Entomostraca found in eastern United States. An immature stage, 

 known as ^^auplijis is shown in fig. 3. 



a. Without a shell-like covering of the body ; with four or five two-branched 

 swimming feet on the thorax, abdomen without appendages. 



COPEPODA. 

 b. Cephalothorax distinctly separated from abdomen, the latter small. 

 c. First antenucC long, about as long as the body, 23-25 segmented ; in 

 the male one is modified into a grasping organ ; fifth feet not rudi- 

 mentar}-. Crntropagid^. 



d. Endopodites of swimming feet composed of three segments, 

 e. Antennte of 23 or 24 segments. Osp/irauticuiii labronectuiii. 



ee. Antennse of 25 segments (fig. 17) Linmocalanus iiiacriirus. 



dd. Endopodite of first swimming feet of one or two segments. 

 e. Endopodite of first, second, third, and fourth swimming feet of one 

 segment. Epischura laciistris. 



ee. Endopodite of first swimming feet of two segments ; of third and 

 fourth feet of three segments (fig. 16). Diapfoiiius. 



cc. Antennse shorter than cephalothorax, with not more than 17 seg- 

 ments ; female with two egg sacks (fig. 20). 



CvCLOPiD^, Cyclops. 



bb. Cephalothorax and abdomen not sharply differentiated ; antennae 



short, at most eight segmented. Harpacticid^. 



With 8-segmented antennae (fig. 19) Canthocamptus. 



aa. Usually with a shell like covering which may or ma}- not entirely cover 



the body ; if without shell the paired eyes are pedunculate. 



b. Trunk limits leaflike in form ; mandible withovit palp. 



PHYLLOPODA. 

 c. With ten or more pairs of trunk limbs, 

 d. Without shell ; paired e^'es pedunculate. The fairy shrimps, etc. 



ANOvSTRACA. 

 e. Clasping antennae of male biarticulate. Frontal appendage present. 



Chirocephawd^. 



f . Frontal appendage of male rather short ; terminal segment of copu- 



latory organ smooth (fig. 21). Eubraiichipus. 



ff. Frontal appendage of male long and vertical ; terminal segment of 



copulatory organ spiny. Branchinella. 



ee. Clasping antennEe of male triarticulate. 



STREPTOCEPHAtiD^. Strepiocephalus. 



* Adapted from Embod}\ Herrick, Van Douwe, et al. 



