1915.] 73 



lateral bristles (sriuroram, mustelae, waikeri), or with one long oiie 

 (fasciatns, londiniensis, penicilliger, melts), besides the long apical 

 bristle (figs. 41,42). 



20. Ceratophyllus fasciatus Botfc (1800). 

 (Figs. 40, 41, 43, 44). 



Rostrum reaching to apex of forecoxa. Occiput with one median 

 bristle. Forefemur with six lateral bristles. Fifth segment of all 

 tarsi slightly shorter than third hindtarsal segment. First pair of 

 ventral bristles of fifth segment more distinctly curved inwards than 

 the other bristles. 



^ . Eighth teigite without hair-like points on inner side. Eighth 

 sternite vestigial. Process of clasper short, broad, triangular. Finger 

 as drawn in figure with two stout and long bristles (fig. 43). 



? . Seventh sternite (fig. 44) , with apical margin slanting and 

 slightly undulating. Lower antepygidial bristle one-fifth shorter than 

 central one. Stylet almost three times as long as broad ; upper lateral 

 bristle absent (fig. 41 j. Eeceptaculum seminis with nearly globular 

 head, which is very much thicker and shorter than tail. 



Generally common in the British Islands. The chief hosts are 

 the Norway rat {E-phnys norvegicus), and the house mouse {Mus 

 musculus) . More rarely examples have been found on several species 

 of field mice and on the weasel {Mustela nivalis), as well as the 

 stoat (Miistela erminea). 



21. Ceratopuyllus londiniensis Roths. (1903). 

 (Figs. 46, 46). 



Paler and smaller than fasciatus, to which it is allied. Bristles 

 on outer side of hindtibia more numerous. Some of the bristles 

 longer than in fasciatus, e.g., longest apical bristle of hindrarsal 

 segment longer than the third segment. 



(^ . Shape of the finger different from that of fasciatus, cf. 

 fig. 46, also arrangement of binstles. Eighth sternite absent. 



? . Seventh sternite produced into a broad truncate lobe (fig. 46). 

 A rare Mediterranean species, probably introduced by port-rats, 

 has occurred on the house mouse {Mus musculus), and possibly on the 

 brown rat {Epimys norvegicus), in London, Dover, and Aber.leen. 



