i] INTRODUCTORY 13 



bat-fleas are rare on their hosts and extremely 

 difficult to find and collect. The same species are 

 not found on fruit-bats and the ordinary smaller 

 insect-eating bats. The geographical distribution of 

 some bat-fleas is puzzling. For instance, one species 

 (Ischnopsylla unipectinata) is found on the greater 

 horse-shoe bat in Europe ; but it is, apparently, not 

 found on the same bat in the British Islands. In 

 Somaliland and in India it is found on other bats. 



With certain exceptions, Ungulates are remark- 

 ably free from fleas. This great order of mammals 

 includes a variety of hoofed animals: oxen, sheep, 

 goats, deer, pigs, camels, giraffes and antelopes. 



The only true fleas found on these are two species of 

 the genus Vermipsylla, which resemble the chigoes in 

 so far that the pregnant females burrow into the host 

 and expand there. One species has been found on 

 camels and horses in Transcaucasia ; another on roe- 

 deer in Northern China. The female of the last is 

 often found ensconced on the inside of the nostrils 

 of the deer. Of course chigoes may attack domestic 

 Ungulates of all kinds; but no other members of 

 the family Pulicidce or typical fleas except those 

 two above mentioned have been found on hoofed 

 mammals. 



Insectivora such as moles, shrews and hedgehogs 

 are the hosts of a great variety of species. The same 

 thing may be said of the Rodents, which include 



