THE CRUSTACEA OF NEW JERSEY. in 



and broad, with stout plumose setae. Eggs numerous, uniseriate, 

 and borne in straight cases, visible for their entire length and 

 usually much longer than body. Mouth-tube elongate and taper- 

 ing to sharp point. First maxillae lacking, second pair simple 

 flattened laminae, tipped with short claws. Second maxillipeds 

 massive and nodose. All four pairs of legs biramose, and some 

 or all of them lamellar and destitute of plumose setae. 



Male. — A typical Nogaus form. Carapace more elongate than 

 that of female, and produced posteriorly into better defined 

 lateral lobes. Free segments all well separated, of about same 

 length, but diminishing regularly in width, and none furnished 

 with dorsal plates. Genital segment also without dorsal plates 

 and little enlarged. Abdomen two-jointed. Anal laminae large 

 and foliaceous, furnished with long and stout plumose setae. 

 Adult males are as free swimmers as any of the CaligincF and 

 move about with as much ease over their host's body, thus afford- 

 ing a marked contrast to the fixed females. The young are 

 attached by two broad and ribbon-like filaments, placed side by 

 side and very short. 



Key to the genera. 



a. Females. All four pairs of legs biramose ; one, three or four, but never 

 two pairs of dorsal plates; abdomen one-jointed and entirely concealed 

 from view. 



b. Rami of first three pairs of legs two-jointed, with plumose setae, of 

 fourth pair one-jointed and setae nonplumose ; four pairs of dorsal 

 plates, fourth on genital segment. pandarus 



bb. Rami of first and second legs two-jointed, of third and fourth pairs 

 one-jointed and very rudimentary ; three pairs of dorsal plates. 



PERISSOPUS 



ca. Males. All four pairs of legs biramose and armed with long plumose 

 setse ; abdomen one or two-jointed, entirely visible. 



c. Both fifth and sixth legs visible on genital segment ; abdomen two- 

 jointed, joints equal. p.\ndarus 



cc. No legs on genital segment, or but one pair: abdomen two-jointed, 

 terminal joint larger. pERISSOPUS 



