PACKARD.] PHYLLOPODS OF NOETH AMEEICA. 351 



Genus CHIROCBPHALUS Prevost. 

 Plate XIII. 



Chirocephalua Tvevost, Journal de Physique, Ivn, 37, 1803; Thompson, Zoological Ee- 



searches, iy34. 

 Brancliipus, Milne-Edwards, Fischer, Latreille, Desmarest, Guerin, Lamarck. 

 Chirocephalus Baird (in part), British Entomostraca, 38, 1850; Annals and Mag. Nat. 



Hist. 2d ser. xiv, 221, 1854 ; Verrill, Proc. Amer. Assoc. Adv. Sc, July, 1870. 



Body slender, head of moderate size, 2d antennae or male ciaspers 

 with the basal joint very large and thick and somewhat curved -, 2d 

 joint very lon^i? and slender, curved inward, with a basal sharp spur. 

 Two remarkably long and large frontal appendages arising between 

 the base of the 2d antennre, about twice as long as the 2d antennae, 

 much twisted and coiled and variously lobed and spinulated. Eleven 

 pairs of swimming feet; the basal iobe or endite long and with the edge 

 regularly curved, the 2d with an outer subdivision about ^ as broad 

 as the 1st ; each paler, with rather long fringe of delicate hair-like setae ; 

 the 2-4 th endites, as in the foregoing genera, small, each with three 

 or four long minutely spinulated seta3. The 5th endite of the usual 

 size, but rather square, much as in BrancMpus, but with a tendency in 

 the lower outer angle to be somewhat produced so as to be subtriaugu- 

 lar in outline. (PL XIII, fig. 1.) The (ith endite is unusually long and 

 narrow, almost lanceolate, and with long setae in the 3d pair of feet, or 

 small, narrow, and abruptly rounded in the 1st pair; in the 10th pair 

 they are narrow and rounded at tip. Flabellum and gills much as in 

 BrancMpus. 



Male genital apparatus short and small, deeply cleft, forming two 

 slender curved portions, each with its cirrus. Caudal appendages long 

 and broad, much more so than in BrancMpus. 



In the female the 2d antennae have the mucronate spur or tip larger 

 and longer than usual. Ovisac short and broad, with the end produced 

 like the neck of a bottle, much as in BrancMpus. The eggs are few in 

 number (about a dozen), and the eggs are larger than in Streptoceplialus 

 and BrancMpus. 



This genus differs from Brancliipus in the slenderer body, the very 

 long, coiled, twisted, lobulated, and spinulose frontal appendages, and 

 in the differences in the endites already noted. In the form ot the ex- 

 ternal male organs and of the ovisac the genus approximates closely to 

 BrancMpus, and in the frontal appendages, as seen in the European G. 

 diaphanus, is only an exaggeration of tliose of Branchipus. It seems 

 reasonable to infer that Chirocephalus is a more recent group than Bran- 

 cliipus, and has probably originated from that genus, as •SLreptocephalus 

 has in all probability arisen from individuals. The singular frontal ap- 

 ])endages are supplied with two large muscles, and as no nerves have 

 as yet been detected in them it is probable that the organs are simply 

 l>rehensile and perhaps of use during the union of the sexes. 



Chuiocephalus noLMANi Ryder. 

 Plate XIII, figs. 1-5. 



Chirocephalus Jwlmani Eyder, Proc. Acad. Nat. Sc, Philadelphia, 148, 1879. 



Body rather slender; 2d antennae or ciaspers of the male with the 

 the 2d joint considerably shorter than the 1st; it is forked, spur 

 large and pointed; the longer branch slender (its tip crossing that of 



