136 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 106 



Seasonal distribution: This species has been collected 

 through the three winter months of January, February, and 

 March and through the late summer and early fall months of 

 August, September, and October. Whether this seasonal pattern 

 indicates population peaks or merely lack of collections during 

 the other months is not known. 



Geographic distribution : The range of E. pivistrelli, as it is 

 known from collections, extends from southwestern Missouri, 

 into Illinois, Kentucky, and Ohio, through southwestern and 

 northwestern Pennsylvania, to southeastern New York (fig. 4,c). 



Diagnosis : E. pipistrelli is the only species with the following 

 combination of characters: Five (or four) prongs on palpal claw, 

 tibiala III present, two genualae I, one pair of indistinct eyes, 

 and nude galeal seta. The very long, heavy, posterolateral setae 

 and the long dorsal setae, sparsely clothed with long setules, are 

 different from those of any other species. 



Ecology: A very limited amount of ecological information is 

 available on E. pipistrelli. It has been collected only from bats 

 which typically inhabit caves. Most of the specimens used in this 

 study were removed from bats which were captured in caves. 



Collectors report the chiggers attached to the inner surface of 

 the ear, on the rim of the ear near the base, on the tragus, near 

 the eyes, on the chin, and at the corners of the mouth. 



Remarks: E. pipistrelli varies in certain characters through- 

 out its range. 



The occurrence of nude and branched setae on the palpal genu 

 is unusual. The list of dorsal setal formulae indicates some of 

 the variation in this character. The shape of the scutum varies, 

 usually by the projection anteriorly of the lateral margins and a 

 narrowing of the distance between the anterolateral and the pos- 

 terolateral setae. 



E. miricoxa Brennan, 1948, was described from a single speci- 

 men, the holotype, removed from a bat, Myotis I. liicifugus (Le- 

 Conte), on Aug. 5, 1947, in Tompkins County, N. Y. This speci- 

 men was not examined in this study. However, from a compari- 

 son of the published description, drawings, and photograph of 

 the scutum with a paratype of E. pipistrelli and other specimens 

 of the species collected in the East, it appears that the range of 

 variation of E. pipistrelli would include E. miricoxa. The extension 

 of coxa I described for E. riiincoxa probably is an apodeme be- 

 neath the integument. It can be found in specimens of E. pipis- 

 trelli and in other species. The shape of the scutum is approxi- 

 mated by scuta of certain specimens of E. pipistrelli. The form and 

 arrangement of the setae is similar in both, so far as can be deter- 



