14 THE FLEA [CH. 



porcupines, squirrels, rats, mice and a vast number 

 of other small mammals whose geographical distri- 

 bution includes almost the whole of the habitable 

 globe. Probably more different species of fleas have 

 been collected from Insectivora and Rodents than from 

 all the other orders of mammals grouped together. 



The Carnivora, excluding the Pinnepedia, or seals, 

 sea-lions and walruses, harbour numerous species. 



Among the Edentata a very remarkable and highly 

 specialised genus of fleas is parasitic on armadilloes 

 in South America. This genus (Malacopsylla) con- 

 sists of two species only, which are confined to South 

 America and are found on the armadilloes and on 

 carnivorous animals which probably have preyed on 

 them. The thorax of these fleas is much reduced 

 and very small in size. Their piercing organs are 

 slender and weak, but they possess enormous spines 

 on the legs with which they hold on to their hosts. 

 These two South American fleas (M. grossiventris 

 and M. androdi) will be referred to again later as 

 striking examples of fleas with strongly developed 

 legs and weakly constructed mouth-parts. The con- 

 trary combination of powerful mouths and degenerate 

 legs is also found in other groups of fleas, as will be 

 seen in the chapter on the chigoes. 



The Marsupials of Australia and South America 

 have special fleas which were probably associated 

 with this strange order of pouched mammals before 



