Finally, it may be well to note here that several palms have been reported from Puerto Rico which probably do not exist in the island; at least their occurrence is not supported by adequate evidence. Thus Mr. R. T. Hill, of the United States Geological Survey, mentions (Bull. U. S. Dept. Agric., Division of Forestry, 25: 1899) as occurring in Puerto Rico seven palms, as follows: _Cocos Mauritia_, _Oreodoxa oleracea_, _Cocos nucifera_, _Martinezia caryotaefolia_, _Mauritia flexuosa_, _Oreodoxa regia_, and _Caryota_ sp., of which list only _Cocos nucifera_ and _Oreodoxa regia_ appear to have been justified. The reference to _Oreodoxa oleracea_ is supported by the botanical authority of Professor Drude, but the specimens identified by him as _Oreodoxa oleracea_ (Sintenis collection, no. 1525) and sent from the Berlin Botanical Garden to the National Herbarium and to the New York Botanical Garden are not _Oreodoxa oleracea_, but belong to the new genus _Acrista_ described below, while a specimen collected by Sintenis (no. 5749) at Aguadilla and sent out from Berlin as an _Attalea_ or related genus is not even a cocoid palm but _Areca catechu_, the betel nut of the Malay region. The existence of numerous tubercles on the roots of a young specimen of the royal palm of Puerto Rico is a fact of biological interest and possible economic importance. It was, however, noted so nearly at the end of our last visit that further studies were not practicable, but barring possible nematodes or other pathological causes for the tubercles it appears that we must add palms to the Leguminosae, _Podocarpus_, _Alnus_, and _Cycas_ as plants which have, as it were, domesticated nitrogen-collecting soil organisms. The field notes, specimens and a considerable series of illustrations for publications of the Department of Agriculture were secured during two visits to Puerto Rico, the first in November and December, 1899, the second in June and July, 1901. The photographs are the work of Mr. G. N. Collins. Key to the Families Leaves fan-shaped; branches of inflorescence subtended by spathes. Family SABALACEAE, p. 529. Leaves feather-shaped; spathes few, not subtending the branches of the inflorescence. Leaf-divisions v-shaped in section, concave above; trunk rough with leaf-bases or prominent diamond shaped scars. Family PHOENICACEAE, p. 528. Leaf-divisions inverted v-shaped in section, convex above; trunk smooth or the leaf-scars ring-like and not prominent. Leaf-bases long-sheathing, green and fleshy, finally split down the side opposite the midrib permitting the leaf to fall; fruits with fleshy, fibrous or woody endocarps. Family ARECACEAE, p. 546.