198 ENTOMOLOGY FOR MEDICAL OFFICERS 



H. pectinata, which occurs on mice and rats, there is only one 

 abdominal comb, situated on the ist tergum. 



Family SarcOPSYLLID^. (Dermatophilidse). 



The following are the necessary genera : — 



1. Hind coxa without a patch of spines on the inner side 



= Dermatophilus {Sarcopsylla). 



2. Hind coxa with a patch of spines on the inner side = Echidnophaga. 



Genus Dermatophilus, Gudrin {^Sarcopsylla, Westwood). 

 The two recognised species of this genus are known as jiggers 



Fig. 83. — Pregnant female of Dermatophilus penetrans, 



and both are indigenous to South America. The male is 

 small, as is the female when not pregnant, and both sexes 

 suck blood. But the female also attaches herself to her host, 

 embedding herself in its skin in a sort of inflammatory pocket 

 from which the tip of the abdomen protrudes for the extru- 

 sion of the eggs. When in this condition (Fig. 83) the 

 abdomen of the gravid female swells to the size of a pea and 

 loses its indications of segmentation, but at the poles (when 

 the animal is removed and examined with a lens) the minute 

 head and thorax and the tip of the abdomen can, in the 

 species that attacks man, though not in the species that 

 occurs on rats, be seen projecting. 



The human jigger {Dermatophilus penetrans), though an 



