CTENOCEPHALUS, HOPLOPSYLLUS, CERATOPHYLLUS 547 



In the male the bristles of the flap-like process of the clasper all 

 slender ; in the female the narrow portion of the receptaculum 

 seminis long. Originally discovered in Egypt. 



This is apparently the chief plague flea. The Indian Plague 

 Committee have proved that this flea is easily infected when fed on 

 plague rats, and that the bacillus multiplies rapidly in the flea's 

 stomach and that the fleas may remain infective for fifteen days. How 

 the flea infects man does not apparently seem to have been proved, as 

 it does not do so through its bite, but the excrement is highly infec- 

 tive. It is probable that this poisoned faecal matter gets to the wound 

 caused by the piercing mouth. 



Xenopsylla brasiliensis, Baker, 

 occurs on rats in West Africa and has been introduced into Brazil. 



Genus. Ctenocephalus, Kolen. 



Includes the cat and dog fleas. The dog flea, C. canis, Duges, 

 is found on the dog" all over the world, but especially in temperate 

 climates. It also occurs on rats. Man is often badly bitten by this 

 insect and it overruns houses. The eggs are laid on rugs, carpets and 

 dust and dirt and amongst dogs' hair, but are not fastened to it and 

 fall anywhere. The ova may hatch in about fifty hours and the larvae 

 live for seven days and then spin their cocoons amongst dust and dirt. 

 The pupal stage lasts about eight days. 



The cat flea (C. fells) is widely distributed over the world, and 

 occurs on many mammals beyond the cat, and is also found on rats. 



Genus. Hoplopsyllus, Baker. 



A genus found in North America related to Pulex, but at once 

 recognized by the prothorax bearing a comb. 



Hoplopsyllus anomalus, Baker, 



which is found on the ground squirrel (Citellus beecheyi) in California, 

 an d according to Rothschild once found on the rat, has been proved 

 to carry the plague bacillus and to play an important part in plague 

 infection in California. 



Genus. Ceratophyllus, Centis. 

 Ceratophyllus fasciatus, Bosc. 



This flea is also found on the rat in Europe and will attack man. 

 It is a plague carrier, It has eighteen to twenty teeth on the 



1 " Report United States Public Health, 1909," xxiv, No. 29. 



