APPENDAGES OF PHYLLOPODA 



plates as in Chirocephalus (Fig. 2), or minute vestigial fila- 

 ments as in Apus, in which genus Zaddach, Huxley, and Clans 

 have all failed to find any trace of a second antenna in some 

 females. In the male Branchipodidae the second antennae are 

 modified to form claspers, by which the female is seized, the 

 various degrees of complication which these claspers exhibit 

 affording convenient generic characters. In Branchinecta each 

 second antenna is a thick, three-jointed rod, the last joint 

 forming a claw, while the 

 second joint is serrate on its 

 inner margin ; in Branchipus 

 the base is much thickened, 

 and bears on its inner side 

 a large filament (perhaps 

 represented by the proxi- 

 mal tubercle of Branchinecta 

 and Artemia), which looks 

 like an extra antenna. In 

 Streptocephalus the terminal 

 joint of the antenna is bifid, 

 and there is a basal filament 

 like that of Branchipus ; 

 in Chirocephalus diaphanus 

 (Figs. 5, 6) the main branch 

 of the antenna consists of 

 two large joints, the terminal 

 joint being a strong claw with 

 a serrated process at its base, 

 while the proximal joint 

 bears two appendages on its 



inner side ; one of these is a small, subconical tubercle, the second 

 is more complicated, consisting of a main stem and five outgrowths. 

 The main stem is many-jointed and flexible, its basal joint being 

 longer than the others, and bearing on its outer side a large, 

 triangular, membranous appendage, and four soft cylindrical 

 appendages, the main stem and its appendages being beset with 

 curious tubercles, ending in short spines, whose structure is not 

 understood. Except during the act of copulation this remarkable 

 apparatus is coiled on the inner side of the antennary claw, the 

 jointed stem being so coiled that it is often compared to the 



FIG. 6. Chirocephalus diaphanus. 

 antenna of male, uncoiled. 



Second 



