142 PROCEEDINGS OF THE NATIONAL MUSEUM vOL. 106 



Remarks: The close morphological similarity between E. 

 samboni and E. oregonensis has been indicated in the descriptions 

 of both species. The localities from which the two have been 

 collected are widely separated in miles but are in the same general 

 geographic area (fig. 4,a). Collections of both species are scant. 

 Further collections are necessary to determine the relationship 

 between the two forms. 



8. Euschongastia peromysci (Ewing) 



Figures 4,a, 5,a,6, ^,c,g,h; Plates 6, 12 



Schdngastia peromysci Ewing, 1929c, pp. 296-297. 



Neoschdngastia peromysci, Ewing, 1931, p. 5. — Radford, 1942, p. 72. — Sig 



Thor and Willmann, 1947, pp. 311, 313. 

 Neoschdngastia signator Ewing, 1931, pp. 14-15, 19, pi. 2, fig. 1. — Radford, 



1942, pp. 72, 74, 75, fig. 80.— Sig Thov and Willmann, 1947, pp. 311, 



313, fig. 374. 

 Neoschdngastia brevipes Ewing, 1931, pp. 16, 19, pi. 2, fig. 4. — Radford, 1942, 



pp. 72, 74, 75, fig. 81.— Sig Thor and Willmann, 1947, pp. 311, 313, fig. 



376. 

 Tromhicula peromysci, Michener, 1946, p. 432. 

 Euschongastia peromysci, Fuller, 1948, p. 108; 1952, p. 184. — Brennan, 1948, 



p. 470. 

 Euschongastia signator, Fuller, 1948, p. 108; 1952, p. 184. 

 Euschdngastia brevipes. Fuller, 1948, p. 108; 1952, p. 183. 



Description: Size: Length, 225 to 750; width, 115 to 565. 



Shape: In life unattached, unengorged chiggers slightly flat- 

 tened oval, widest at the third pair of legs; engorged, oval. Pre- 

 served on slides, oval to ovoid. 



Color : Unengorged chiggers, cream or light yellow ; engorged, 

 opaque white. Red eyes. 



Gnathosoma : Seta on palpal femur strong, cui'ved, well clothed 

 with setules except on the concave margin. Seta on genu curved, 

 with two or three rows of strong, alternately arranged setules 

 on the convex curvature. Dorsal seta on tibia curved, with two 

 alternate rows of setules; lateral seta with a few setules which 

 tend to arise near the base ; ventral seta with about five alternate 

 rows of strong setules over the dorsal surface of the shaft. Setules 

 on all setae appear strong and stiff. Palpal claw slightly curved, 

 three-pronged, the middle prong longer and heavier, the two 

 accessories arising near middle of the claw and lying close against 

 the median prong; length somewhat variable through the range 

 of the species (fig. 5,6). Galeal seta of distinctive appearance, 

 curving, bristlelike, usually with one to three stiff setules arising 

 on the outer margin near the base; number of setules variable 

 within about the same limits throughout the range with a ten- 



