CHIGGERS — FARRELL 



163 



of distinct eyes, a scutum marked by three joined ridges, cuticular 

 striae folded over the posterior margin of the scutum, and capitate 

 sensillae. As the genus is known at the present time, the form of 

 the ridges on the scutum is sufficient to set off the "rubra" group 

 from other North American species, as follows: Two inverted, 

 somewhat V-shaped ridges — one anterior to each pseudostigma — 

 with a third ridge extending anteriorly around the anterior 

 median seta connecting the apexes of the first two. 



10. Euschongastia rubra, new species 



Figures 4,6, 6,a,d; Plates 2, 4, 7, 13 



Description : Size : Length, 276 to 722 ; width, 165 to 554. 



Shape: Ovoid in unengorged specimens in life, broader pos- 

 teriorly, becoming oval with engorgement. Unengorged specimens 

 preserved on slides, ovoid; engorged specimens preserved on 

 slides, broadly oval. 



Color: Light red in unengorged specimens, becoming pink, 

 orange, and yellow with increasing engorgement; always with 

 deep red eyes. 



Gnathosoma : Seta on palpal coxa with strong fringe of setules 

 on outer curvature. Strong, forward-curving seta on palpal femur 



Table 7. — Distribution of setules on the galeal setae by pairs of setae for 

 121 specimens of Euschongastia rubra 



(Each fisrure is the number of setules on one seta of the pair; x indicates a seta broken off) 



with numerous setules evenly distributed except on concave mar- 

 gin, which tends to be nude. Strong curving seta on palpal genu 

 with numerous setules in about four alternate rows on its convex 

 curvature. Dorsal seta on palpal tibia strong with setules in one 

 or two rows on its outer curvature ; lateral seta shorter, strongly 

 pectinate or with setules alternately arranged on its outer curva- 

 ture; ventral seta long and strong with numerous setules alter- 

 nately arranged over the longitudinal dorsal half of the shaft. 

 Palpal claw strong, curved, three-pronged with median prong 

 longest and strongest; accessories strong, arising about one-half 



