CHIGGERS — FARRELL 129 



Legs : Similar to E. lacerta. Genu I with two genualae, one dor- 

 sal and one posterior, and a rather long microgenuala. Microspur 

 I proximal to spur. Spur 1 more distal than in E. lacerta. Tibialae 

 shorter than in E. lacerta. All leg segments with conspicuous 

 punctae. 



Scutum : Generally similar to that of E. lacerta. Anterior mar- 

 gin concave with a slight convexity near the anterior median seta. 

 Lateral margins more concave than in E, lacerta and the four 

 corners more elongated. Pseudostigmata much closer together. 

 Sensillae missing from specimen. Punctate. Cuticular striae ap- 

 pear to encroach on lateral margins. 



Standard data of the holotype, from Galveston County, Tex. : 



Eyes : Corneas of anterior eyes distinct ; diameter, 9 ; posterior 

 eyes indistinct. No ocular plate. 



Dorsal setae : Similar to E. lacerta. Length of a humeral seta, 

 35; of a seta from the first posthumeral row, 36; of a posterior 

 seta, 20. 



Dorsal formula of the holotype : 2.6.6.6.6.4. 



Ventral setae: More numerous than in E. lacerta. Length of 

 a first sternal, 25 ; of a second sternal, 18 ; poststernals all about 

 the same length, 18. 



Ventral formula of the holotype: 2.2 plus about 40. 



Material: Holotype only, USNM 1989. From host: 



Sigmodon sp. 



Galveston County, Tex., Aug. 8, 1947. 



Diagnosis: E. bigenuala differs from E. lacerta, the other 

 member of the "lacerta" group, by lacking ocular plates, by hav- 

 ing two genualae I, and by having its microspur I proximal to 

 the spur. 



Remarks: Only one incomplete specimen of E. bigenuala has 

 been collected. The very important sensillae are missing. How- 

 ever, the morphology of the group is so unusual and the correla- 

 tion of Euschongastia bigenuala with it is so complete that there 

 can be little doubt of its position. E. bigenuala is named for the 

 two genuala I which distinguish it from E. lacerta. 



3. Euschongastia nunezi (HofTmann) 



Plates 6, 10 



Neoschdngastia nunezi Hoffman, 1944, pp. 221-225, figs. 1-4. — Nunez, 1947, 



pp. 221-237, 241-244, figs. 1-31. 

 Euschongastia nunezi, Fuller, 1952, p. 184. 



