Palms of Puerto Rico 539 



so far as known, have the segments much broader, both absolutely 

 and relatively, and the width is held for a very much smaller pro- 

 portion of the length. 



In addition the midrib is unusually weak, inconspicuous and 

 only slightly prominent on the lower side. The small fibro- vascu- 

 lar bundles which compose it are sometimes spread apart so that 

 there is scarcely an indication of a rib while in other segments of 

 the same leaf, and especially at the base, the conditions are more 

 normal. The midrib is sufficiently distinct above, though very 

 small and fine in comparison with other species. 



Lower surface of leaf glabrous or somewhat glaucous, very 

 slightly puberulous on the depressed veins near the base. Vein- 

 lets inconspicuous, mostly subequal, though 4 or 5 are sometimes 

 a little larger than the others. Transverse veinlets indistinct below. 



Petiole slender, 4 mm. wide, lenticular in cross section ; about 

 2 mm. thick. Ligule small and weak, short, with a small apical 

 mucro. 



Fruits 5 mm. in diameter, olive brown, irregularly rugose-cori- 

 aceous on the outside as though dried from a pulpy condition ; 

 exocarp with a slightly sweetish taste. Seed bright mahogany- 

 brown, darker below, depressed-globose, with a sublateral raphe ; 

 embryo ascending but more nearly lateral than vertical ; conical 

 basal cavity extending somewhat above the center, nearly filled 

 with a deep red material. 



At the time of our visit in July no ripe fruits of T. Ponceana 

 were found on the trees, but a few picked up from the ground are 

 apparently indistinguishable from those of Sintenis' specimen. 



Thrincoma gen. nov. 



Trunk slender, tapering, flexible ; wood firm, covered by a 

 smooth hard brittle outer shell or bark. 



Leaf bases long-sheathing, expanded by the separation of the 

 fibers of the side opposite the midrib ; petiole strongly flattened 

 above the base, prominently angled above and below ; ligule large 

 and firm, produced laterally to support the outer divisions. 



Leaf-divisions narrow, separated below the middle and below 

 the point of greatest width; texture firm and coriaceous ; veinules 

 subequal, close together, cross-vein ules obsolete. Lower surface 

 clothed with persistent closely appressed hairs, the upper coated 

 with wax when young. 



