The species here figured are all from the Rio Negro, where I began studying them, and are sufficient to give an idea of their general characteristics and aspect. [Illustration: Pl. XXVIII. W. Fitch lith. Ford & West Imp. BACTRIS PECTINATA. Ht. 8 Ft. ] PLATE XXVIII. BACTRIS PECTINATA, _Martius_. Iú, _Lingoa Geral_. The stem of this species is from six to ten feet high, very slender, strongly ringed or jointed and smooth, but all other parts of the plant, the petioles, sheaths, spathes, &c., are prickly. The leaves are regularly pinnate, with the leaflets long, narrow, pointed and hairy beneath. The long sheathing bases of the petioles are persistent, covering the stem often half way down to the ground. The spadices grow from among the persistent leaf-sheaths; they are very small, simple or two- or three-branched, and have a small persistent fibrous spathe. The fruit is very small and globular and of a red colour, and is not eatable. This very hairy and prickly little palm grows in the sandy Catinga forest of the Upper Rio Negro and in the most exposed localities. It seems to agree well with the _B. pectinata_ of Martius. A fruit is shown on the Plate of the natural size. [Illustration: Pl. XXIX. W. Fitch lith. Ford & West Imp. BACTRIS —— Ht. 12 Ft. ] PLATE XXIX. BACTRIS ——, n. sp. Marayarána, _Lingoa Geral_. The stem of this species is about an inch in diameter and ten or twelve feet high, thickly set with flat black spines disposed in rings. The leaves are rather large and irregularly pinnate, the leaflets being in little groups of two or four, standing out at various angles from the midrib, the groups themselves being set alternately along it. The leaflets are elongate and have the midrib produced in a bristly point, and the terminal pair are not larger than the rest. The petioles are armed with flat whitish spines, which on the long sheathing bases become black. I met with this palm only once, growing in the dry virgin forest on the banks of the Rio Negro. Though it had neither flowers nor fruit at the time, yet its habit is so peculiar as to leave little doubt of its being a new species. It seems most nearly allied to the _Bactris macroacantha_ of Martius. [Illustration: Pl. XXX. W. Fitch lith. Ford & West Imp. BACTRIS ELATIOR. Ht. 20 Ft. ] PLATE XXX. BACTRIS ELATIOR, n. sp. Marayarána, _Lingoa Geral_.