REVISION OF THE SARCOPS YLLIDAE 
25 
some Echidnophaga (for instance in E. macronycbia and E. gallinaceus) the eye is placed 
but little nearer the groove than it is in Hectopsylla, or rather the strip of chitin sepa- 
rating it from the groove is but little narrower. In Echidnophaga larina and bradyta, 
however, the eye approaches the groove closely, while in Dermatopbilus it is also placed 
near the groove (Fig. G). As this apparent difference in the position of the eye 
depends on the development of the anterior edge of the antennal groove, there is a 
corresponding difference in the size of the latter, the groove being larger in those 
species whose eyes stand at the groove than in those in which the groove is covered 
to a greater extent by the more developed anterior edge. 
The antennal groove in the Sarcopsyllidae is open behind as it is in the genus 
Pulex, the hinder edge of the occiput not being sufficiently raised behind the groove 
as to being contiguous with the genal lobe (PI. I, Fig. 1-5). In Echidnophaga 
larina, however, that edge is so much elevated as to practically close the groove. The 
space between the genal lobe and the occiput is in Pulex filled in by the prosternite, 
the genal lobe being very short. A similar structure obtains in Dermatopbilus (Fig. G), 
while in Hectopsylla and Echidnophaga the genal lobe is so long — or has become 
secondarily so much prolonged — as to separate more or less completely the prosternite 
from the antennal groove, as is the case also in Ctenocephalus canis and felis. 
The antennae of the Sarcopsyllidae resemble very closely those of Pulex pallidas-, 
cleopatrae, and some other African species. The second segment is strongly 
asymmetrical as in those species, being produced apically into a large obtuse projection. 
On this projection we find in Echidnophaga as in Pulex pallidas, irritans, and others a 
number of long bristles of about equal length, while in Hectopsylla there is one long 
bristle accompanied by several somewhat shorter ones, Dermatophilus agreeing closely 
with Echidnophaga, except in the bristles being thinner. The club of the antennae 
is connected with the second segment by a short conical stalk, the third segment. 
The club consists of eight segments as in other Siphonaptera. It shows in the 
Sarcopsyllidae a conspicuous specialization, also present in Pulex pallidas, cleopatrae, 
nubicus, etc. In these two groups of species the segmentation of the club is entirely 
restricted to the posterior side, there being no indication of segmentation on the 
anterior side. Pulex irritans, Ctenocephalus canis, and felis somewhat resemble Pulex 
pallidas and the Sarcopsyllids in the fusion of the segments of the club, the segmentation 
being in these species faint but visible on the anterior side of the club. The club of 
the species of the genera Vermipsylla, Chaetopsylla, Lycopsylla and Malacopsylla is 
completely segmented as in Pulex cleopbontis, leporis, etc., no other Siphonaptera having 
attained such a high degree of fusion in the segments of the antennal club as the 
Sarcopsyllidae and the Old World species of the genus Pulex allied to pallidas and 
cleopatrae. 
In Echidnophaga the solid anterior side of the club bears a row of usually three 
short hairs with another short hair placed below, as is the case in Pulex pallidas and 
E 
