S84 PROCEEDINOS OF THE NATIONAL MUSEUM. vol.xxvii. 



It seems soniethino- of an iinoiiialy to tind two species so elosel}'^ 

 related on such ditferent hosts. If but one or a few specimens had 

 been found on the lynx, I should have considered the occurrence acci- 

 dental and surmised that these specimens were originally from some 

 rabbit, ])ut Professor Aldrich took a large series. Much more collect- 

 ing- will be necessar}' to throw any definite light on the matter. 



Ti/pe.—Cat No. 6899, U.S.N.M. 



Genus CTENOCEPHALUS Kolenati. 



1859. Ctenocephalus Kolenati, Fauna V. Altvaters, j). 65. 

 1863. Clenocephalus KohEtiTi, Horse See. Ent. Ross., II, p. 44. 



The species grouped under this heading are essentiall}" Pulex with 

 ctenidia on the gena?. The presence of the ctenidium on the head 

 may, perhaps, be an artificial character, but it is at least a definite one. 

 That the grouping is an artificial one there is no question. The new 

 anornalus must go into Pulex, but it is more closely related in many 

 ways to sinij)le,r and inpequalis^ also rabbit fleas. Every lot of new 

 species alters one's ideas of the relationships. We know, as j'et, but 

 a lamentably small proportion of existing species. 1 would not care 

 to attempt a recasting of these groups on such very fragmentary data, 

 especially when this present arrangement can be well employed for 

 the time being. 



SYNOPSIS OF SPECIES. 



a. Spines of head ctenidia in longitudinal rows on lower margins of gense; head not 



tuberculate in front canls (p. 384). 



aa. Spines of head ctenidia in o])lique rows on hind margins of gente; head tubercu- 

 late in front. 

 h. Mandibles reaching three-fourths of anterior (!ox;e; head ctenidia in male with 



eight spines on each side simplex (p. 385). 



hh. Mandibles slightly exceeding anterior cox*; head ctenidia in male with four 

 or five spines on each side bncqualis (p. 385). 



CTENOCEPHALUS CANIS Curtis. 



The common cat and dog flea is probably the most widely distrib- 

 uted mend)er of the order, occurring practically wherever cats and 

 dogs occur. Dr. Lutz sends specimens from Brazil. It seems to be 

 a normal and abundant parasite of cats and dogs, but has been found 

 on a variet}' of other animals. It occurs commoid}' as a transient 

 guest on almost all of the domesticated, semidomesticated, or caged 

 animals, and will bite human Ijeings whenever opportunity offers. 

 Many reported cases of infestation of houses have been found to be 

 due to this species, rather than to Pulex irrltans. The case of a lot 

 of fleas collected by Mr. Snyder from a fox at San Diego, California, 

 offers a peculiar instance of unusual occurrence. A part of this lot 

 proved to be Pulex irritans and the rest this species. 



