In the following paragraphs an effort is made to clarify those terms (in italics) which are most frequently used by the writer in describing chiggers. The capitulum (gnathosoma of authors, false head) consists of palpi and chelicerae and the supporting and protective structures of the latter. The palpi (pedipalps) are five-segmented. The first segment, visible only in ventral view, is fused dorsally. Ventrally, it bears a plumose seta which is constant in all species known to me and appears to have no taxonomic significance. Palpal segment 2 is large, usually outwardly bowed and sometimes subangulate laterally. It has one dorsal seta, palpal seta 1. Segment 3 has one dorsolateral seta, palpal seta 2. Segment 4 normally has three setae, one dorsal, one lateral and one ventral. These are designated as palpal seta 3, palpal seta 4, and palpal seta 5 in order of their origin from proximal to distal end of the segment. This segment is terminated by a claw with apical elements called prongs. Segment 5, the palpal thumb, arises from the inner anteroventral portion of segment 4 so that it apposes the palpal claw. Five or more setae and a bare striated spur are present on the thumb. This spur has been referred to as a sensory seta, and may have a sensory function, although there appears to be no evidence to support the suggestion. The chelicerae consist of two elements: a proximal, robust supporting base, base of chelicera, and a distal heavily sclerotized blade-like structure, chelicera, which is terminated by one or more teeth. Ventrad of the chelicera is a broad sheathing structure, cheliceral shield (galea ?), bearing a single anterolateral seta. A dorsal plate, the scutum, occupies an anterior position on the dorsum. The scutal setae are designated according to their respective positions on or near the margins. In addition to the setae, the scutum bears a pair of specialized organs, the sensillae, arising from pits or cup-like structures, the sensillary bases. These structures have been referred to respectively as the pseudostigmatic organs and the pseudostigmata.