882 AN INTRODUCTION TO ENTOMOLOGY 



AA. Abdomen without apical spines on the tergites; inner surface of anterioi 

 portion of hind coxae with one row of small spines, rarely with more than one 

 row. 

 B. Thorax longer than the head, not shorter than the first abdominal tergite, 



P- 882 PULICID^ 



BB. Thorax shorter than the head, also shorter than the first abdominal 

 tergite. p. 882 Echidnophagid^ 



Family CERATOPHYLLID.i; 



This family includes those Integricipita in which there are small, 

 sharply pointed spines on the apices of some of the abdominal tergites. 

 It is represented in this country by many species ; these infest various 

 rodents, mink, birds, and man. 



Family PULICID^ 



This family inchides those Integricipita without apical spines on 

 the abdominal tergites in which the thorax is longer than either the 

 head or the first abdominal tergite. It includes some of our most 

 common and best-known species; among these are the following? 



The cat-flea, Ctenocephalus felis. — This is the species that is most 

 often found in our dwellings in the East and in the South, and the 

 one that most often attacks man in these regions. Both the genae 

 of the head and the pronotum are armed with ctenidia; the genal 

 ctenidia extend from the antennal groove to the anterior margin of 

 the head. The first spine of the genal ctenidia is about as long as 

 the second. This species infests dogs as well as cats. 



The dog-flea, Ctenocephalus canis. — This species is closely allied 

 to the cat-flea, but in this species the first spine of the genal ctenidia 

 is only about one-half as long as the second spine. This flea infests 

 dog, cat, and man. 



The human flea, Pulex irrltans. — On the Pacific Coast this is the 

 species that is most often found in houses attacking man. It is 

 easily distinguished from the two preceding species by the fact that 

 its head and thorax lack ctenidia. Man is its natural host; but it 

 will infest various other animals temporarily. 



The Indian rat-flea, Xenopsylla cheopis. — Among the various spe- 

 cies that are supposed to transmit the bubonic plague, this cosmo- 

 politan species is regarded as one of the more important. It resembles 

 the himian flea in lacking ctenidia, but can be distinguished from 

 that species by the fact that the mesostemite is broad, with a rod-like 

 internal thickening extending from the insertion of the coxa upward. 



Hoplopsyllus anomalus. — This is the plague carrier, of the Cali- 

 fornia ground squirrels, and it also infests rats. In this species there 

 is a ctenidium on the pronottmi, but none on the head. 



Family ECHIDNOPHAGID^ 



In this family the thoracic segments are short, the three segments 

 together being shorter than the first abdominal segment in the dorsal 



