464 



MEDICAL ENTOMOLOGY 



Ceratophyllus fasciatus. The common rat flea of the colder parts of 

 Europe, but found also in the tropics in the colder parts of the year. 



Ceratophyllus anisus. Represents the above species in Japan. 



Ctenopsylla mitscidi. The flea of the house mouse, Mus musculus, but 

 occurring also on rats. 



Ctenopthalmus agyrtes. The flea of the field mouse and vole. It is 

 also found on rats living in similar situations. 



Some idea of the proportions of these species found in different local- 

 ities may be obtained from the following table, taken from the Reports 

 of the Indian Plague Research Commission. It has been compiled from 

 a large number of records made by different observers. 



Percentage of total fleas belonging to each species. 



The figures given above probably exaggerate the prevalence of cheopis, 

 as this species is specially common on rats taken in the neighbourhood 

 of shipping, where most of the counts were made. Slight differences in 

 the locality from which the rats were taken may make considerable 

 alterations in the proportions of fleas present, on account of the change 

 in the environment of the host. 



Different species of fleas appear to select different regions on the body 

 of the host, a point which is well brought out by counts of rat fleas, 

 mainly from Mus norvegicus, made by McCoy and Mitzmain in California, 

 as shown in the following table : 



fasciatus 

 3'3 per cent 



Fore Quarters 

 Hind Quarters 



10'5 

 86'2 



cheopis 

 7'7 per cent 

 6'8 

 85'5 



musculi 

 87 '2 per cent 

 12'2 



'6 



Most of the fleas on dogs and cats are found about the abdomen. The 

 flea of the Indian squirrel is generally found about the rump. In the 



