30 
The Non-Combecl Eyed Siphonaptera 
project from the cavity formed by this sclerite. The genitalia are very 
small in Loemopsylla, the outline of the various projecting parts being 
difficult to make out in unmounted specimens except in a few species. 
These accessory copulatory organs are portions of the ninth segment. The 
central dorsal area of this tergite bears the sensory plate as in the $ , the 
sides of the tergite being modified into clasping organs. This lateral 
portion, of which the main part may conveniently be called “clasper,” 
is in Loemopsylla not separated from the dorsal portion by a suture. 
The lower inner angle of the clasper is produced inwards into a slender 
manubrium, which does not present any very striking differences in the 
various species of Loemopsylla , except in length (PI. IV, fig. 6, M). Above 
the manubrium the inner edge of the clasper usually bears a slight 
tubercle-like projection. On the outer side of the clasper there are in 
Loemopsylla , Moeopsylla and Pariodontis three processes (P 1 , P 2 , P 3 ), of 
which two are movable, being connected with the clasper by a joint, 
while the third is often reduced or absent. These processes are very 
characteristic of the three genera mentioned, and are of great value in 
the discrimination of the species. They correspond to the large flap and 
the pair of pincers found in Pulex irritans (see Jordan and Rothschild, 
1906, p. 38). The American non-combed eyed Pulicidae have a large 
clasper with one movable process, the manubrium being also large 
(PI. VI, fig. 7). The ninth sternite is always strongly modified in 
Siphonaptera. In its most general form it is boomerang-shaped in side- 
view, consisting of an internal vertical, and a ventral horizontal arm, the 
latter projecting outside the eighth sternite. The vertical arm extends 
upwards to the base of the manubrium of the clasper, lying on the outer 
side of the manubrium, there being a vertical arm on each side of the 
abdomen. The horizontal arm is in Pulicidae either separated in the 
mesial line as far as the junction with the vertical arm, or there is no 
such separation into two ventral sclerites. In Loemopsylla as in Pulex, 
Moeopsylla and Pariodontis the sternite is much reduced, the vertical 
arm sometimes not reaching the clasper. The ventral arm is divided 
into two slender processes, which are different in shape in the various 
species. This double process is moved by means of a long chitinous rod 
projecting far into the abdomen. The clasping organs appear to be 
always the same on both sides of the abdomen in Siphonaptera, apart 
from slight differences such as every two sclerites may present. 
Between the clasper and the ninth sternite the penis projects, the 
chitinous parts of which are very complicated (PI. IV, fig. 6, Pen.). The 
outline of the internal elongate plates—one on each side—varies more or 
