ART. 20. STUDIES OF THE BITING LICE — EWING. 15 



compact and heavily chitinized ; basal plate very long with straight, 

 parallel sides ; parameres clawlike, being outwardly hooked. Second 

 and third pairs of legs practically identical; anterior fork of a 

 femoral tenaculum simple, except for transverse striations, but pos- 

 terior fork with a conspicuous, sharp, seta-bearing tubercle. 



Length of female, 1.03 mm. ; width, 0.52 mm. Length of male, 0.90 

 mm.; width, 0.35 mm. 



Type host and type locality. — Cavia cohaya probably living under 

 conditions of domestication. 



Described from an abundance of material from various hosts. 

 This species has followed its type host through the process of do- 

 mestication and probably to all civilized countries of the world, but 

 in nature is restricted with its host to the neotropical region. Rec- 

 ords from hosts living in a natural state are here given. A male and 

 female combed from a Cavia skin (Cat. No. 236344, U.S.N.M.: Biol. 

 Surv. Collection) taken at Las Palmas, Chaco, Argentina, August 1, 

 1920, by A. Wetmore ; several specimens representing both sexes from 

 skin of Cavia tschudi pallidior male (Cat. No. 221015, U.S.N.M.), 

 taken originally at Arequipa, Peru, by W. E. Castle ; one female from 

 a dragon fly {Ischnogomphus jessei Williamson) taken at Cresta- 

 lina, Colombia, February 15, 1917, by J. H. and E. B. Williamson 

 (Dr. W. M. Mann has published an article on the finding of this and 

 other specimens of the same species on this dragon fly). Kellogg 

 in his catalogue and host list published in Genera Insectorum in 

 1908 gives Caviu cohaya as the only host species. This is the only 

 host mentioned by Mjoberg (1910), Neumann (1912), and Kellogg 

 and Ferris (1915). 



GYROPUS FORFICULATUS Neumann. 



Plate 1, fig. 2. 



A medium-sized stout species with conspicuous setae. Head about 

 as broad as long; temporal lobes somewhat projecting; antennae 

 rather larger than usual and completely filling the long deep antennal 

 fossae; palpi small and not reaching the anterior margin of the 

 large labium. Above the head bears a transverse row of six, large, 

 subsequal setae on the temporal region. Prothorax about equal to 

 the head in width, its anterior margin straight, lateral margin at 

 first almost straight and subparallel, then about straight but strongly 

 converging posteriorly. At the anterior corners of the prothorax is 

 a pair of long curved setae; about half a dozen equally long setae 

 are borne above. Mesothorax, which is not very distinctly separated 

 from the metathorax, is much smaller and narrower than the pro- 

 thorax, and constitutes the narrowest part of the bodv. Meta- 



