Aeria gen. nov.
A tall slender palm evidently related to Gaussia, but the embryo lateral instead of basal, and the pinnae without basal cushions.
Among palms in Puerto Rico Aeria resembles only Acrista, from which it is readily distinguishable by the very slender habit, the swollen base of the trunk, the much-branched slender interfoliar inflorescence, the shorter sheathing bases of the leaves, and the numerous spathes.
The embryo of Aeria is located near the longitudinal middle of the seed on the side opposite the rudiment of the style, which is here located at the base of the fruit instead of on the side as in Acrista. The albumen is also uniform, except for a small central cavity and the outer covering is fleshy rather than fibrous.
The position of the embryo is, perhaps, the most obvious difference between this genus and Gaussia, but there are several other significant discrepancies. Thus the flowers are arranged 3 or 4 in a row, very seldom 5 or 6. Three fruits develop from one flower only exceptionally. The trunk is of more than medium height, and the inflorescence is in reality infrafoliar, for although the dead leaf-bases and midribs of the leaves are persistent and support the long inflorescence, this condition is not comparable to that of the cocoid and other really interfoliar inflorescences.
Aeria attenuata sp. nov. [Plate 45.]
The tallest of Puerto Rico palms, probably attaining 30 metres and upward. The trunk is supported on a mass of coarse roots with spine-like projecting rootlets arranged in whorls. The surface of the trunk is smooth with very faint annular impressions. Near the ground the diameter is 12 to 15 cm. and increases upward to about 25 cm. at about 3 m. above the base. Above this swelling the trunk tapers very gradually and in tall specimens is less than 7 cm. in diameter at the top.
The sheathing leaf-base is only 20 cm. long. The leaves remain attached long after the rupture of the open side, but no fibers are formed, the edges of the split side being fringed only with brown membranous shreds. The petiole is rather short, round and rigid and the rachis is prominently angled above.
Segments of a rather firm texture and standing in different planes, but all more or less upright or oblique to the rachis, segments from middle of leaf 2.3 cm. wide near the base, 3.8 cm. long. The segments are set very closely together, especially the proximal, and overlap each other in a succubous manner. Fresh fruits deep orange in color and of an unsymmetrical oval in shape, 16 mm. by 12 mm., with a firm, fleshy outer covering 1.6 mm. thick, adherent to the seed, the three persistent styles remain of the same size and are located at the base of the fruit.
The seed is flattened oval, 11 mm. by 9 mm., with a prominent basal tubercle (hilum). The surface is brownish with a few shallow impressed lines, but the albumen is white and uniform. Flowers and ripe fruit were obtained at Vega Baja in December, 1899; type specimen no. 1040.