26 PROC. ENT. SOC. WASH., VOL. 23, NO. 2, FEB., 1921 



in texture to those in the case of other species and their location is but slightly 

 different. The longest apical spine on the posterior tibia is about two-thirds 

 the length of the first tarsal segment. The plantar bristles of all the tarsi are 

 arranged in five pairs, all lateral. The relative lengths of the tarsal segments 

 are shown by the following table: 



Legs. Segments 1-5. 



I 24 14 10 8 17 



II 36 22 12 8 17 



III 68 52 30 18 24 



Modified segments. The eighth sternite is produced posteriorly into a scoop- 

 shaped process, thickly set with fine short hairs. The ninth sternite is club 

 shaped and on the ventral margin toward the apex there are a number of stout 

 teeth, mostly in pairs. The movable finger of the clasper is elongate, thickest 

 slightly beyond the middle. On either side, toward the posterior margin there 

 is a straight row of about fifteen hairs, reaching from the apex to about basal 

 third. The fixed process is obliquely rounded above and bears a few hairs. The 

 eighth tergite is trapezoidal in shape, with many long bristles and shorter hairs 

 toward the upper portion. 



9 Essentially similar to the male in vestiture. Antepygidial bristles are 

 four on each side. Compared with H. schefferi Chapin, its length is one-third 

 greater, conical teeth of the abdominal segments are 7, 2, 2 instead of 8, 4, 3, 

 and the body of the receptaculum seminis is nearly square (11:10) instead of 

 rectangular (14:8). 



Length: c? 7.38 mm.; 9 "7.53 mm. 



Types. Type cf , Allotype ? collected off Aplodontia cali- 

 fornica Peters, at Mammoth, Mono County, California, July, 

 1917, by A. B. Howell. Paratype taken at Indian Canyon, 

 Yosemite National Park, California, probably from Aplodontia 

 sp. by Dr. G. F. Ferris. Type and paratype in Collection 

 Ferris, allotype in my collection. 



At this time it seems best to correct an unfortunate error in 

 my description of H. schefferi. Owing to the contracted con- 

 dition of the specimen it is almost impossible to determine the 

 exact limits of the abdominal tergites. The small combs of 

 short conical teeth do not occur on the third, fourth and sixth 

 segments as stated but on the second, third and fourth as in the 

 present species. 



There are now four species of this genus known, of which one 

 is palaearctic in range (H. talpac Curtis). The remaining three 

 are found in western North America. For specimens of H. 

 dippiei Rothsch., I am indebted to Mr. J. O. Martin of Berkeley, 

 Calif., who has collected this species in the nests of Neotoma 

 fuscipcs. The following key will serve to separate the four 

 species. 



1. Ctenidia of abdominal tergites composed of small tooth-like spines which 

 are in close-set rows; genal ctenidium of more than ten spines; palae- 

 arctic ...talpac Curtis. 



