4. Meaostemite very narrow, without internal rod-like incrassation from the insertion 



of coxa upward Pulex. 



Mi'sostcrnifc wilh a rod-like internal incrassation from the insertion of coxa 

 upward ." Xenopsylla. 



5. Eyes rudimentary; female with two to five antepygidial bristles each 



side Neopsylla. 



Eyes distinct; female with but one antepygidial bristle each side . . . Ctenocephalus. 



Hoplopsyllus, one species, described as a Pulex. 

 Hoplopsyllus anomalus Baker. 



The mandibles scarcely reach halfway down on the anterior coxse; 

 upon each are two large spines; the pronotal comb has about nine 

 spines each side; and each abdominal segment has but a single row 

 of bristles. The hind femora have six to eight bristles on the side; 

 the proportions of the joints in the hind tarsus are: 26-16-8-5-13. 

 Color, dark reddish brown. Female, 2.5 millimeters; male, 1.5 mil- 

 limeters. 



Described from a spermophile from Colorado and recorded by 

 Doctor Fox and Professor Doane from Mus norvegicus from California. 

 Pulex. Of this, the typical genus of the family, but one species has 



been recorded from rats. 

 Pulex irritans Linn. 



The mandibles reach about halfway down on the anterior coxse; 

 the head is regularly rounded in front; there are no transverse rows 

 of bristles on the vertex, and but one row of bristles on each abdominal 

 tergite. The proportions of the joints in the hind tarsus are, 50- 

 30-18-12-32. Color, usually yellow brown. Male, 1.6 to 2 millime- 

 ters; female, 2 to 3.5 millimeters. 



This, the human flea, is quite cosmopolitan, but more abundant in 

 warm countries than elsewhere. It occurs on many domestic animals 

 and has frequently been taken from rats in California and elsewhere; 

 it also occurs 011 skunks. 

 Xenopsylla. This genus includes the following species, formerly 



placed in the genus LoemopsyUa. 

 Xenopsylla cheopis Rothschild. 



The mandibles reach nearly to the end of the anterior coxae; there 

 are no ctenidia on the head or pronotum; the eyes are distinct; each 

 abdominal tergite has but one row of bristles; the hind femur has a 

 row of about eight bristles; the proportions of the joints in the hind 

 tarsus are as follows: 46-30-16-10-20. Color, light brown. Male, 

 2.5 to 3.5 millimeters; female, 4 to 5.5 millimeters. 



This is a true rat flea, but will readily bite man, and is the species 

 chiefly concerned in transmitting the bubonic plague. It is widely 

 distributed, especially in seaport tow r ns. 



Ceratophyllus . Fleas of this genus are abundant on many kinds of 

 small mammals, especially rodents. There are a great many species 



