426 PROCEED TNGS OF THE NA TIONA L MUSE UM. vol. xxvii. 



limb obtuse. In this case it is very deep, deeper than broad, and the 

 outer subtending limb is narrowly acute. On the lifth tarsal joints 

 are combined the characters of two of the Wagnerian genera; on the 

 fore and middle last tarsal joints the first pair of spines is dislocated 

 toward the median line and directed straight distad. On the hind last 

 tarsal joint there are but four spines on either side. 



While I am somewhat loath to separate any new genera at this time 

 when the inflow of strange and aberrant forms has just begun, still, in 

 this case there is hardly any other course open to me, for otherwise 

 imdata might be placed with equal propriety in any one of two or 

 three genera. 



ANOMIOPSYLLUS NUDATUS Baker, 



This species, the smallest known American flea, was originally 

 described from two females collected at Tucson, Arizona, in a nest of 

 Neotoma aJhlgula hj the late Mr. Hubbard, who was one of the most 

 thorough collectors America has yet seen. In addition to the charac- 

 terization originally given, the following additional details may be 

 noted: 



The lower row of genal bristles is represented by one very weak and 

 slender bristle on margin of antennal groove and a similar one on the 

 lower margin of the head. There are no other bristles on the head 

 excepting one or two at each lower angle of hind margin, and a very 

 few short ones on second antennal joint. The thorax is without bristles 

 excepting one on either side of pronotum at each lateral angle. 



The abdominal tergites each have a single row of about six very 

 weak and slender bristles. One small and slender antepygidial bristle 

 occurs on either side. The hairs on pygidium are very fine, but 

 longer than usual. 



Style about three times longer than wide at base, and slightly nar- 

 rowed to the tip, where there is a long bristle. The substylar flap is 

 long and acute and has numerous bristles on the lower margin. Below 

 the substylar flap a number of short, stout bristles occur near the 

 margin. 



The first joint of the hind tarsi has four groups of spines on the 

 anterior margin and two groups on the posterior margin. One of the 

 spines on apex of second joint of hind tarsi posteriorly is very long 

 and slender, extending nearly to the end of the last joint. Lengths 

 of hind tarsal joints in the proportions 18-10-6-5-10. 



Length, 2 mm. Color, pale lirown. 



Genus CTENOPSYLLUS Kolenati. 



1863. C/t'nopsz/Hws Kolenati, Hone Soc. Ent. Koss., II, p. 37. 

 1893. Ctenopsyllus Wagner, Horse Soc. Ent. Ross., XXVII, p. 350. 



This is preeminently the genus of mouse and rat fleas. Elsewhere 

 has been noted the extreme paucity of knowledge on the American 



