ii. Base of the capitulum (fig. 151) usually hexagonal (except in the male of _puchellus_); and usually inornate. j. No ventral plate or shield in either sex (fig. 153). R. BICORNIS from the United States. RHIPICENTOR Nuttall jj. Males with a pair of adanal shields, and usually a pair of accessory adanal shields. Numerous species, among them _R. sanguineus_ (fig. 154) and _texanus_, the latter from the United States. _Rhipicephalus_ Koch hh. Anal grooves faint or obsolete; no marginal festoons. i. Short palpi; highly chitinized; unfed adults of large size; coxæ conical; male with a median plate prolonged in two long spines projecting caudad; segments of leg pair IV greatly swollen (fig. 155, 156). _M. winthemi_ _Margaropus_ Karsch [Illustration: 152. Monieziella (Histiogaster) emtomophaga-spermatica, ventral aspect, male and female. After Trouessart.] ii. Very short palpi, ridged dorsally and laterally; slightly chitinized; unfed adults of smaller size; coxæ I bifid; male with adanal and accessory adanal shields (fig. 139). B. ANNULATUS. BOOPHILUS Curtis ff. Palpi longer than broad (fig. 157). g. Male with pair of adanal shields, and two posterior abdominal protrusions capped by chitinized points; festoons present or absent. Several species, among them H. ÆGYPTICUM (fig. 140) from the old world. HYALOMMA Koch gg. Male without adanal shields but small ventral plaques are occasionally present close to the festoons. Many species, a few from the United States (fig. 157). AMBLYOMMA Koch h. Coxa I with but one spine; metatarsi (except I) with two thickened spurs at tips. _A. maculatum_ hh. Coxa I with two spines; metatarsi without stout spurs at tips, only slender hairs. i. Projections of coxa I blunt and short. Large species on the gopher tortoise in Florida. _A. tuberculatum_ ii. Projections of coxa I longer, and at least one of them sharp pointed; second segment of palpus twice as long as the third; coxa IV of the male with a long spine. j. Porose areas nearly circular; shield of both sexes pale yellowish, with some silvery streaks and marks, and some reddish spots; shield of female as broad as long. A. CAJENNENSE (= MIXTUM).