In diameter the trunk appeared to be about midway between the palma de sierra (_Acrista_) and the cocoanut, and had the short internodes of the latter. The leaves, however, probably remain somewhat smaller than those of _Acrista_ to which they might also be said to have a general similarity, except at the base where their cocoid proclivities become obvious. At a little distance _Cocops_ might be overlooked as _Acrista_, while at shorter range it might be mistaken for a very depauperate cocoanut. No species of _Cocos_ is, however, known to be native in the West Indies except the doubtful _Cocos crispus_ H.B.K., from Cuba. As a species _Cocops rivalis_ may prove to be similar to _Syagrus amara_ (Jacquin), which is reported as far north as Jamaica, but it seems to have no true generic affinity with _Syagrus cocoides_ Martius, the South American palm which is the type of its genus. According to Martius _S. amara_ is 30 cm. in diameter, as large or larger than _Cocos nucifera_ and attains the height of from 20 to 35 meters; _Syagrus cocoides_, on the other hand, is a small slender palm with a trunk 2.5–3 m. high and 5–7.5 cm. in diameter, and with foliage and habit resembling the slender and diffuse South American species referred by Martius to _Cocos_, but very different from _Cocos nucifera_ or from _Cocops_. A leaf collected by Sintenis (no. 6061) near Camuy and coming from Berlin labeled _Oreodoxa_, obviously did not originate with an arecoid palm, but probably belongs with the present species. The region of Camuy is but a few miles from Lares, but there is much extremely rough and unoccupied country between, so that the danger of extermination appears to be somewhat diminished. Explanation of Plates PLATE 43. _Thrincoma alta_, top of type specimen (no. 848). PLATE 44.. _Thrincoma alta_, part of leaf and seeds, natural size. PLATE 45.. _Thrinax Ponceana_, type (no. 1005). PLATE 46.. _Acrista monticola_, type (no. 761) collected near Adjuntas. PLATE 47.. Fig. 1, _Aeria attenuata_. Fig. 2, _Cocops rivalis_ (left) and _Roystonea Borinquena_ (right). PLATE 48.. _Curima colophylla_, apex of flower-cluster and terminal leaf-division, natural size. From type specimen (no. 878). [Illustration: PL. 43. THRINCOMA ALTA HELIOTYPE CO., BOSTON. ] [Illustration: PL. 44. THRINCOMA ALTA HELIOTYPE CO., BOSTON. ] [Illustration: PL. 45. THRINAX PONCEANA HELIOTYPE CO., BOSTON. ] [Illustration: PL. 46. ACRISTA MONTICOLA HELIOTYPE CO., BOSTON. ] [Illustration: PL. 47. AERIA ATTENUATA COCOPS RIVALIS ] [Illustration: PL. 48. CURIMA COLOPHYLLA HELIOTYPE CO., BOSTON. ] ----- Footnote 1: This spelling and the adjective use of the name in this form are editorial corrections. Footnote 2: