120 FOX. 



It is interesting to note that not one example of Ceratophyllus 

 fasciatus Bosc. or of Ctenopsylla musculi Duges was observed. 

 This series, taken with Herzog's, would indicate that Xenop- 

 sylla cheopis is practically the only rat flea present in the Phil- 

 ippine Islands or at least in Manila. It is not improbable that 

 conditions of temperature and humidity in the Tropics are inim- 

 ical to the multiplication of Ceratophyllus fasciatus or Ctenop- 

 sylla musculi which seem to be fleas of the temperate zone. On 

 the other hand Xenopsylla cheopis, which is primarily a flea 

 of the Tropics, finds little difficulty in adapting itself to the 

 conditions of a cooler climate. 



The following brief description of the rat flea in Manila will 

 sufl^ce to identify it as Xenopsylla cheopis. 



Head. — Noncombed-eyed. Two bristles on the gena, 1 in front 

 of eye, 1 on lower genal edge. Occiput contains a subapical row 

 of 6 bristles on each side with 2 behind the antennal groove. 

 The rostrum reaches to the apex of the fore coxae. 



Thorax. — The mesosternum bears 5 bristles. The episternum 

 of the metathorax is separated from the sternum and bears 1 

 bristle, the epimerum 2 rows of bristles, about 7 in the first row 

 and about the same number in the second row. 



Abdomen. — Each tergite has a single row of bristles, as have 

 also the sternites. There is one subapical (antepygidial) bristle 

 on each side of the seventh segment which is much longer than 

 the second hind tarsal segment. 



Legs. — There is a comb of about 6 teeth on the inner side of 

 the hind coxa. On the inside of the hind femur there is a row 

 of 5 to 9 bristles, and on the outside 2 subapical bristles. The 

 second mid tarsal segment is twice as long as the third. The 

 longest apical bristle of the second hind tarsal segment reaches 

 to the middle of the fifth segment. 



Modified segments. — $ The clasper has 2 free processes, one 

 slender, finger-like, the other much broader and well rounded and 

 bearing long bristles on its upper margin and apex. 



9 Along the apical edge of the eighth tergite there are about 

 12 bristles with an inside row of about 8, and an irregular row 

 on the lateral surface of about 9 bristles. 



A full description of Xenopsylla cheopis may be found in 

 articles by Jordan and Rothschild* and by others.^ 



'Parasitology (1908), 2. 



'The Rat and its Relation to the Public Health. U. S. Public Health 

 and Marine-Hospital Service, Washington (1910). 



