34 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63. 



liypopharyngeal chitinization (fig. 15) with anterior horns strongly 

 divergent, each provided distally with five teeth and along its inner 

 margins with minute serrations. Prothorax almost as broad as 

 head; mesothorax and metathorax completely united and together 

 a little longer and a little broader than the prothorax. Abdomen 

 more slender in the male than in the female ; first segment apparently 

 divided into two by the presence of two transverse rows of dorsaP 

 setae. If this apparent division of the first segment were considered 

 a real one the actual number of abdominal segments would be nine 

 instead of eight. Genital armature of female as in G. distincta ex- 

 cept the lateral chitinizations, or apodemes, are stouter. Male genital 

 armature reaching the posterior border of third abdominal segment ; 

 basal plate not broadened at its base and with sides parallel; para- 

 meres almost straight except near their distal ends, each paramere 

 rounded at its tip where are situated three minute setae. Legs 

 about subequal; tarsus I (pi. 1, fig. 8) with first segment about as 

 broad as long and distal segment soft, pulvilluslike with transverse 

 lines; at the base of second tarsal segment are two seta-bearing 

 tubercles, one being on the inside and one on the outside. These 

 setae are straight. 



Length of female, 1.18 mm.; width, 0.3 mm. Length of male, 

 1.03 mm.; width, 0.27 mm. 



Type host and type locality. — From Cavia cohaya., probably in a 

 state of domestication. 



Description based on many specimens from four different species 

 of CavHi. Kellogg (1908) gives only Cavia cohaya as a host for this 

 species, all records coming evidently from domesticated animals. 

 Mjoberg (1910) reported, " /iY/r/^^; ExcDiplare von Cav'm cohaya 

 {ipse) iind von''eine'ni schwarzen Meerschwein.''''' Neumann (1912) 

 described a new subspecies of G. porcelU from Kerodon moco col- 

 lected at Para, Brazil. This subspecies may prove to be a good 

 species. The writer has not seen examples of it. The material in 

 the United States National Museum, exclusive of collections from 

 the domestic guinea pig, are as follows: A female and nymph on 

 Cavia tschtidii (female) from La Raya Pass, Peru, November, 1915: 

 four females and a transforming male, determined by Paine as 

 G. hicaudatus^ on Cavia cutlerl^ from Peru, by Castle ; several speci- 

 mens from Cavia rufescetis in the same cage with C. cohaya., October 

 2, 1912; three females from Cavia tschudii pallidior (male) (Cat. 

 No. 221015, U.S.N.M.) which died in 1919 at the National Zoo- 

 logical Park, Washington, D. C, the animal being originally taken 

 at Arequipa, Peru, by W. E. Castle. 



GEOGRAPHICAL AND HOST DISTRIBUTION. 



The family Gyropidae is probably the most interesting in its 

 geographical and host distribution of all the families of the order 



