(3 The N'on-Combed Eyed Siphonaptera 
reaching about halfway down the forecoxa. The labial palpus consists 
of 4 segments. 
Thorax. Thoracic tergites short, each with one row of bristles; no 
subapical spines on the mesonotum. Prosternum widest close before 
apex. Mesosternite characteristic, very narrow, its ventral edge strongly 
oblique, the stigma not being entirely covered; no internal rod-like or 
cariniform incrassation from the insertion of the coxa to the dorsal 
edge. Episternum of the metathorax not quite separated from the 
sternum, the suture being indicated anteriorly only by an internal 
incrassation. 
Abdomen. Convex in both sexes, dorsally as well as ventrally. 
The first tergite with two rows of bristles, the other tergites with one; 
the seventh with one long bristle a little before the apical edge. 
Stigmata large. 
Legs. Midcoxa narrow, the internal rod-like incrassation dividing 
near base. Hindcoxa pear-shaped, long, being widest near base, hairy 
in front and behind on inner side, and bearing a row or patch of short 
spines near apex. First fore- and mid-tarsal segment shorter than 
second. 
Modified segments. </: 8th tergite with small manubrium as in 
Echidnophaga. Clasper bearing a very large flap, on the inside of 
which there are two processes forming a kind of claw as in the 
Sarcopsyllidae; manubrium of clasper large, curved. Ninth sternite 
boomerang-shaped, its upper inner end pointed. Internal wire-like 
spring of ninth sternite and penis making several coils.— $ : no hairs 
above the stigma of 8th tergite. Stylet with long apical bristle and 
a short bristle before apex. Anal sternite truncate, the bristles confined 
to the apical edge. 
This genus contains one species only, parasitic on man. In many 
respects it is the most specialized of all the Pulicidae and resembles in 
some characters the Sarcopsyllidae. The chief character of this insect 
is the greatly reduced thorax, the mesosternite especially being highly 
specialized. The pleura of this sternite is narrow and strongly oblique 
and lacks the internal cariniform incrassation found in other fleas. This 
incrassation usually extends from the suture of the coxa upwards to the 
anterior corner of the pleura, but it is absent from P. irritans and from 
some of the Sarcopsyllidae. In compensation for this loss the anterior 
ventral portion of the mesosternite ( i.e. the sternum) is much 
strengthened inside. The peculiar structure of the genitalia 
separates irritans from all allied genera and links it with the Sarco- 
