_A. brevipes_ Banks, a species with proportionately shorter legs has been recorded from Arizona. ff. With another combination of characters. About six other species of _Argas_ from various parts of the world, parasitic on birds and mammals. ee. Body flattened when unfed, but usually becoming very convex on distention; anterior end more or less pointed and hoodlike; margin thick and not clearly defined, similar in structure to the rest of the integument and generally disappearing on distention; capitulum subterminal, its anterior portions often visible dorsally in the adult; eyes present in some species. f. Integument pitted, without rounded tubercles; body provided with many short stiff bristles; eyes absent. On horses, cattle and man (fig. 48). OTIOBIUS Banks. O. MEGNINI, a widely distributed species, is the type of this genus. ff. Integument with rounded tubercles or granules; body without stiff bristles. ORNITHODOROS Koch. g. Two pairs of eyes; tarsi IV with a prominent subterminal spur above; leg I strongly roughened. On cattle and man. O. CORIACEUS gg. No eyes; no such spur on the hind tarsi. h. Tarsi I without humps above. _O. talaje._ hh. Tarsi I with humps above. i. Tarsi IV without distinct humps above. On hogs, cattle and man. O. TURICATA ii. Tarsi IV with humps nearly equidistant (fig. 142). Africa. O. MOUBATA [Illustration: 149. Hæmaphysalis wellingtoni. Note short palpi. After Nuttall and Warburton.] dd. With scutum or shield (fig. 50); festoons usually present; coxæ usually armed with spurs, tarsi generally with one or two ventral spurs; pulvilli present in the adults; sexual dimorphism pronounced. IXODIDÆ e. With anal grooves surrounding anus in front; inornate; without eyes; no posterior marginal festoons; venter of the male with non-salient plates. Numerous species, 14 from the United States, among them I. RICINUS (fig. 49 and 50), SCAPULARIS, COOKEI, _hexagonus_, _bicornis_. IXODES Latr. (including Ceratixodes). ee. With anal groove contouring anus behind, or groove faint or obsolete. f. With short palpi (fig. 149). g. Without eyes, inornate, with posterior marginal festoons; male without ventral plates. Numerous species. _H. chordeilis_ and _leporis-palustris_ from the United States. _Hæmaphysalis_ Koch.