4 American Midland Naturalist Monograph No. ] 



the Southwestern United States and parts of Mexico. While not known to be 

 concerned in the transmission of any disease, the habit of the immature stages 

 of feeding deep in the ears of the host results in intense irritation. Heavily 

 infested animals, especially calves, are often in poor condition and deaths of 

 cattle have been attributed to gross infestations of this tick. Several instances 

 have been reported of the occurrence of nymphs of this species in the ears of 

 man. Medical attention is usually required to effect the removal of the tick. 



Explanation of Terms 



Fig. 1 



Anterior Projection: The projection of the dorsal body wall at the anterior end. 

 It may extend horizontally or may be curved ventrad and be continuous with or 

 separate from the hood. 



Anus: The external evidence of the termination of the alimentary tract, located on 



the venter back of the coxae. It consists of two eversible flaps enclosed in a 



continuous ring or frame. 

 Apical Ventral Spur: A ventral spur on the distal end of the tarsus in some species. 



Figure 53, D and E. 

 ARTICLE: A distinct articulating portion of a leg or palpus. The sequence of the articles 



is indicated by Arabic numerals 1, 2, 3 and 4, 1 being proximal. 



Attenuated: To become thin, fine, or less. 



Basis Capituli: The basal portion of the capitulum which is movably articulated 

 with the body and to which the mouth parts are attached. The "basal ring" of 

 some authors. 



Buttons: In the genus Argas, circular elevations found on the integument, each with 



a central pit and often with a hair in the pit, and distinguishable from the discs 



and "wrinkles." 

 Barbed Hairs: Tapering hairs with barbs on their sides. The barbs may be numerous 



and found on all sides or few in number and present on one side only, and may 



be long or very short. Fig. 52 H. 



Camerostome: The depression or cavity in which the capitulum lies, and usually 

 less definite in much engorged specimens. 



Capitulum : The movable anterior portion of the body including the mouth parts. 

 The "head" or "false head" of some authors. 



Cheeks: Paired flaps at the sides of the camerostome, which may be either fixed or 

 movable; the "movable cheeks" of some writers. Fig. 1, C. 



Chelicerae: Paired mouth parts for piercing the skin, lying dorsally on the hypostome 

 and completing the more or less cylindrical mouth parts that are inserted when 

 the tick feeds. 



CLUBBED Hairs: Hairs which do not taper and are terminally enlarged. 



Color: The color is greatly affected by ingested blood. At first there is a reddish 

 tinge resulting from the fresh haemoglobin but in a few hours this changes to 

 dark gray. During the subsequent process of depletion the changing color of the 

 blood gradually loses its effect and only the natural color of the body wall 

 remains. Color is much affected when the specimen is placed in preserving fluid; 

 also those preserved soon after feeding appear different from those preserved 

 after having been depleted for weeks or months. Thus, since the color is not 

 dependable, it is usually not mentioned in describing the Argasidae. 



Corona: The apical portion of the hypostome which is differentiated from the 

 remainder by having very small denticles which may be numerous or few in 

 number. 



Coxae : The sequence of the coxae from anterior to posterior is indicated in Roman 

 numerals thus, I, II, III, and IV. Fig. 1, B. 



