430 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxvii. 



CTENOPSYLLUS MEXICANUS Baker. 



It was expected thiit the ilea found on Mus rattus at Guanajuato, 

 Mexico, by Dr. Duge.s, would turn out to l)e some European species. 

 It proved, however, to differ materially from anything described. 

 Later. Dr. Duges sent further material from Mu>< norcegleus taken at 

 the same place. The following notes may be added to the original 

 description : 



Female: Dorsal segments with small teeth on hind margins as fol- 

 lows: Six on metanotum, six on lirst abdominal tergite, four on second, 

 four on third, and two on the fourth. Antepygidial bristles four in 

 each set, the first inner one and third shortest, second longest and 

 largest, fourth nearly as long as second. One stout bristle occurs on 

 either side below pygidium. 



The style is rather long and narrow, the length twice the width at 

 base, narrowing gradually to the apex, where there is a long bristle; 

 another bristle nearly as large occurs on the lower margin. The sub- 

 stylar flap has a number of bristles near the apex, mostl}^ on lower 

 margin. 



The hind margin of posterior tibse bears three long spines and a close- 

 set straight row of about fifteen short spines. The apical spines on 

 second joint of hind tarsi are shorter than the third joint. The first 

 pair of spines on last joint of hind tarsi dislocated toward median line 

 and directed straight caudad. 



Length, 2.5 mm. Color, pale brown. 



Male: Antepygidial bristles, three on either side; the middle one of 

 each group longest. The eighth segment on either side below bears 

 but five bristles. 



The lateral portion of the ninth tergite is strongly constricted 

 below the pygidium, then expanded into a symmetricall}^ rounded limb 

 which in outline is shaped like a pestle. There is but a single bristle 

 over the insertion of the claspers. The upper claspers are small but 

 stout, thumb-shaped, with the ball of the thumb turned caudad, not 

 extending above the lateral portion of the ninth tergite, and with four 

 or Hve bristles on the hind margin. 



Length, 2 mm. 



Genus STEPHANOCIRCUS Skuse. 



1890. Stephanodrcus Skuse, Records of Austral. Mus., II, p. 77, pi. xvii. 



1895. Stephanodrcus Baker, Canad. Ent., XXVII, p. 63. 



1896. Stephanodrcus Skvs^, Records of Austral. Mus., II, p. 7. 



The original description of this remarkable genus came to me just 

 as the Preliminary Studies were being published. I copied the 

 description and remarked that it presented such an anomalous struc- 

 ture and such a remarkable case of sexual dimorphism that I would 

 not attempt to place it in Taschenberg's system, which I was then com- 



