SPECIES OF XENOPSYLLA 453 



from the insertion of the coxa to the dorsal edge. The hind coxa is 

 pear-shaped, and bears a number of hairs situated on the inner surface 

 of the posterior portion. 



GENUS XENOPSYLLA, GLINK. 

 (Syn. Loemopsylla, Rothsch.) 



The palpi are four-segmented; the antennal groove closed, antennae 

 solid in front ; the pleura of the mesosternite (Plate LV, fig. 2) divided by 

 a suture into a sternal and a meral portion ; the dorsal apical bristle of 

 the seventh abdominal tergite remote from the edge of the segment ; there 

 are short spines on the inner surface of the hind coxa, and the division of 

 the rod-like incrassation inside the mid coxa takes place near its base. 

 The clasper of the male has two or three small processes ; the manubrium 

 is narrow ; the upper internal portion of the ninth sternite is not sharply 

 defined. In the female the stylet bears, besides the long apical bristle, 

 a short bristle situated in a notch before the apex. (Jordan and 

 Rothschild). 



This genus derives its importance from the fact that one of the species, 

 X. cheopis, has an important relation to plague. It contains in all 

 twenty-four species, most of which are found in Egypt and the Egyptian 

 Soudan, some few coming from Central Asia. They are essentially 

 parasites of rodents, and the plague flea, now found in all parts where 

 the climate is suitable, has been transported from place to place on rats, 

 usually by means of ships. 



The following key to the species is from Jordan and Rothschild. 



KEY TO THE SPECIES OF XENOPSYLLA 



a. Frontal portion of head with one or two long bristles . b 



Frontal portion of head with six long bristles .... chcphrcnsLs. 



b. Episternum and sternum of metathorax not separated from 



each other by a suture ; hind femur with or without tooth 

 ventrally at the widest point ..... c 



Episternum and sternum of metathorax separated from each 

 other by a suture ; hind femur with tooth ventrally at the 

 widest point ; . . . . g 



Episternum and sternum of metathorax separated from each 

 other by a suture ; hind femur without a tooth ventrally 

 at the widest point ....... o 



c. Hind femur with a tooth ventrally at the widest point . d 



Hind femur without this tooth longispinis. 



d. Fourth segment of hind tarsus short, triangular in outline. e 

 Fourth segment of hind tarsus elongate . ... f 



