GENERA OF THE PULICIDAE 



451 



flea and the rat fleas of tropical countries, which are of special interest 

 .in connection with the spread of plague. These have been exhaustively 

 dealt with by Jordan and Rothschild. 



The following key, which is a compilation from the keys of Jordan 

 and Rothschild, Rothschild, and Baker, will serve for the identification 

 of the commoner genera. The first group mentioned above is constituted 

 by the first nine genera, the second group by the remainder. 



KEY TO THE PRINCIPAL GENERA OF THE PULICIDAE. 



1. Fleas with or without eyes, and with genal or pronotal comb, 



or both .......... 



Fleas with eyes, and without genal or pronotal comb 



2. Club of antenna distinctly segmented only on the hind side 

 Club of antenna distinctly segmented all the way round 



3. With comb on the pronotum only ...... 



With pronotal and genal comb ...... 



4. Eye developed ......... 



Eye vestigial or absent ....... 



5. No comb on head ........ 



Two spines at angle of gena ....... 



6. Pygidium not projecting backwards. Frons with tubercle 

 Pygidium strongly convex, projecting backwards. Frons with 



tubercle .......... 



7. Abdomen without comb 



Abdomen with at least one comb ...... 



8. Hind edge of tibiae with about eight short and several long 



bristles, which do not form a comb ..... 

 Hind edge of tibia with about twelve short and three long 

 bristles, the short ones forming a sort of comb . 



9. Fifth segment in fore and mid tarsi with five and in hind tarsi 



with four lateral bristles ....... 



Fifth segment in fore and mid tarsi with four and in hind tarsi 

 with three lateral bristles, there being an additional pair in 

 all tarsi on the ventral surface in between the first pair 



10. Club of antenna short, distinctly segmented only on the 



posterior side. Antennal groove closed behind, the genal 

 process separating the antennal groove from the fore coxa. 

 Labial palpus consisting of four segments ; tip of rostrum 

 asymmetrical. Hind coxa with a comb of spines on the 

 inner side. Antipygidial bristle separate from the apical 

 edge of the seventh tergite . ... 

 Club of antenna segmented all roundi the antennal groove open 

 behind, the genal process being short. Hind coxa without 

 row of spines on the inner side. Labial palpus distinctly 

 segmented all round, consisting of four to seven segments, 

 the tip of the last being symmetrical. One antipygidial 

 bristle, standing at the edge of the segment, which is sinuate. 



11. Mesosternite very narrow, without rod-like incrassation from 



the insertion of the coxa upwards ,:l*ii . . _ ...- ... . . 



2 



10 



3 



4 



Hoplopsyllus. 

 Ctenocephalus. 



Chiastopsylla. 

 Ceratophyllus. 



Pygiopsylla. 



8 

 Hystrichopsylla. 



9 



Ctenopsylla. 

 Neopsylla. 



Ctenophthalmus. 



11 



12 



Pulex. 



