75 



It has been recorded by Doctor Fox from Mus rattus in California; 

 and is known from rats and mice from several parts of Europe; the 



0. italicus Tiraboschi is the same species. 



The four other species of this genus found on rats and not yet 

 found ia our country are closely related to 0. fasciatus, and distin- 

 guished chiefly by the shape of the male genitalia. 

 Ceratophyllus mustelse. Wagner. 



This species has no series of hairs on the inner surface of the hind 

 femur;. there are three bristles in front of the eye and six in front of 

 these; the pronotal comb has 18 or 20 spines; the proportions of the 

 joints in the hind tarsus are 47-37-20-13-20; the movable finger 

 of the male clasper has a long process below not seen in other forms. 

 Occurs (according to Rothschild) on rats in Europe. 

 OeratofJiyllus pencilUger Grube. 



This species also has no hairs on the inner surface of the hind 

 femora. The pronotal comb has 18 spines; there are three bristles in 

 front of the eye and four in front of these; the proportions of the 

 joints in the hind tarsus are 52-36-23-14-24; the outer corner of the 

 movable finger of the male clasper has two little rounded processes. 

 It was described from Siberia, but according to Rothschild occurs 

 on rats in Europe. 

 Cerato'phyllus consimilis Wagner. 



This species is very close to 0. fasciatus, and has some fine hairs on 

 the inner surface of the hind femur; there are but two bristles in front 

 of the eye and in front of these a few finer hairs; the proportions of 

 the joints in the hind tarsus are 42-30-20-11-19; pronotal spines 18. 

 Occurs on rats in Russia. 

 Ceratophyllus lagomys Wagner. 



This species also has a few fine hairs on the inner surface of the hind 

 femur; 18. spines in pronotal comb; there are three bristles in front of 

 eye and one in front of these; the proportions of the joints in the hind 

 tarsus are 53-32-20-11-22; the outer corner of the movable finger 

 of the male clasper has two little processes, similar to those on 

 C. penciUiger. Occurs on rats in Europe. 



Gtenocephalus. — The common fleas on cats and dogs, as well as on 

 man, belong to two species long kept under one name {0. canis or 

 G. serraticeps) , but lately shown by Rothschild to be distinct. Both 

 have a comb of 8 spines on the head and 16 spines in pronotal comb; 

 the proportions of joints in the hind tarsus are 40-24-15-10-24. 

 Both are occasionally taken on rats in this country. They may be 

 separated as follows : 



1. In the female the head is fully twice as long as high (seen from side); the first spine 



of genal comb is two-thirds the length of the second; in raale the manubrium of 

 claspers is barely enlarged at tip; and with two rows of hairs on disc of movable 

 finger C.felis Bouche. 



