38 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
Ceratophyllus the sternite is intermediate in size, while in others again it is large. The 
Sarcopsyllidae have the eighth sternite similar to that of Pulex irritans and its allies. 
The sternite is much longer ventrally than it is dorsally, and is therefore much arched 
ventrally. In one of the new Sarcopsyllids it is modified in a peculiar way, as is 
described in the body of this paper (PI. II, Fig. 19). The large eighth sternite 
forms a kind of cover for the genitalia proper, protecting them ventrally and anally 
when the $ crawls beneath the $ and bends the abdomen upwards for the purpose of 
copulation. The enlargement or the eighth sternite and the curvature of its ventral 
surface can thus be readily understood. The great reduction of this sternite in so 
many species of Ceratophyllus is, however, difficult to explain from the utilitarian 
point of view. In Hectopsyl/a (PI. II, Fig. 17 and 18) as well as Dermatopbilus 
(Fig. F, p. 56) the eighth sternite of the $ is very deeply sinuate on each side. 
The clasping organs are portions of the ninth segment. The tergite of 
this segment consists of three main portions, a dorsal part with the sensory 
plate upon it, to which we shall refer hereafter, and on each side a lateral part, called 
the clasper, bearing several appendages. These claspers are as a rule not separated 
F 
Fig. E 
from the dorsal part of the tergite by a suture, but are continuous with it. However, 
in some instances (Chaetopsy lla) there is a suture between the clasper and the dorsal 
portion of the tergite separating them almost entirely. The clasper with its 
appendages can be best understood we think by comparing it with that of Pulex irritans, 
which represents in our opinion a more generalized type than the clasper of the other 
Pulicidae. The ninth tergite (Fig. E) is proximally produced into a long process (M) 
acting as a lever or handle, the manubrium, as it is termed by Wagner. Above this 
manubrium there is another process which is very small and belongs to the eighth 
tergite, which tergite is much reduced in P. irritans. This small process or manubrium 
of the eighth tergite is found only in Pulex irritans and leporis, and again among the 
Sarcopsyllids in the genus Echidnopbaga, the process being absent from all the other 
