Cylindrdpsyllus brevicorni?, d;c. 135 



lon^ as the precedino; segment in tlie female. Anal oper- 

 culum not prominent, and without spines. The furcal rami 

 are twice as long as they are broad, with a laige apical seta 

 which is nearly one-tliird the length of the body. All the 

 segments oP the body are smooth, without spines, but there 

 are groups of exceedingly minute cilia on the ventral side 

 of the al)doniinal segments (PI. V. tig. 1) and a pair of 

 minute set.e on the dorsal mai-gin of each (PI. Y. fig. 3). 



The first antenna (PI. VI. fig. 1) of the female is short 

 and consists of five joints, the first two being thicker than 

 the remainder and forming a distinct basal part. The third 

 aiul fourth joints are short, the fourth bearing a thick 

 aesthete extending far beyond the end of the antenna. The 

 distal joint is as long as the third and fourth comljiued, and 

 armed at its apex with two setae and an sesthete, the latter 

 springing from the same base as one of the setae. In the 

 male the antenna is not geniculated and appears to be com- 

 posed of two joints only, since the two bas;il joints are fused, 

 and the remaining joints are only partially distinct. Viewed 

 from above, the last three joints appear completely fused, 

 the long aesthete springing from the edge of a peculiar notch, 

 which probably serves as a hook for grasping the female 

 (PI. VI. figs. I'l, 12). 



The second antenna is the same in both sexes and consists 

 of three joints (PI. VI. figs. 2, 3). The second joint bears 

 two small set?e in place of the external ramus, which is 

 absent. I have seen one specimen in which this joint, in 

 both limbs, bore a long blunt-pointed seta (PI. VI. fig. 3). 

 The distal joint is armed. with five or six strong claws and 

 a pair of setse which spring from the same basis. One of 

 these setae has a bifurcated tip, and in some specimens there 

 appears to be a hyaline prolongation with a bead at the end 

 similar to the aesthetes of the antennae of Cladocera. 



The mouth-parts (text-fig. 1) consist, as in Cijlindropsyllus, 

 of three pairs of appendages only, the maxillipedes being 

 absent. In C. Levis there are a pair of minute triangular 

 plates behind the second pair of maxillae which, as Prof. 

 Sars suggests, may represent the maxillipedes, but there is no 

 trace of them in Horsiella. The mandible consists of a large 

 quadrangular base anil a slender chewing part with three or 

 four blunt teeth, no trace of an external ramus being found. 

 The first maxilla has a two-jointed jialp and a single broad 

 terminal lobe armed with three teeth and a few spines. 

 The second maxilla is two-jointed, the ba*<al part bearing, in 

 place of the usual setigcrous lobes, a single finger-like 

 process with a comb of minute hook-like spines. The second 



