24 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



SPERMATOPHYTA. 

 Order ARECALES. 



Family ARECACEAE. 



PALM RAYS. 



The broken rays of apparently two species of palms occur spar- 

 ingly in the Culebra formation at the locality one-fourth mile south 

 of Empire Bridge. These are too incomplete for even tentative 

 generic determination. 



Genus PALMOXYLON Schenk. 



Group LUNARIA. 



PALMOXYLON PALMACITES (Sprengel) Stenzel. 



Plate 12, fig. 1. 

 Endoyenites palmacites Spkengel, Commentatio, p. 39, figs. 6, 6a, 1828. 

 Fasciculites palmacites Cotta, Dendrol., pp. 49, 89, pi. 9, figs. 1, 2, 1832.— 



Ungeb in Martius, p. 59, tab. geol. 3, fig. 6, 1845. 

 Palmacites dubius Coeda, Beitrage, p. 42, pi. 22, 1845. — Schimpee, Pal. 



Vgget., vol. 2, p. 513, 1870 ; Hanclbuch, Abst. 2, p. 887, 1892. 

 Palmacylon tenerum Felix, Foss. Holzer Westindiens, p. 26, pi. 4, fig. 1, 



1883.— Schenk in Zittel. 

 Palmoxylon palmacites S ten gee, Foss. Palmenholzer, p. 245, pi. 20, fig. 253, 



1904. 



Description. — Fibro-vascular bundles small, very numerous, closely 

 spaced, orbicular or ovate in cross section, uniformily distributed as 

 a rule, 0.60 mm. to 0.75 mm. in diameter, and rarely, if ever, that 

 distance from one another. Auxiliary bundles absent. 



Sclerenchyma portion excavated more or less deeply to receive the 

 vascular portion, which is often nearly equal to it in size. Occa- 

 sionally a thin zone of sclerenchyma entirely surrounds the vascular 

 portion. Sclerenchyma fibres small, isodiametric, greatly thickened, 

 of nearly uniform size, about 0.035 mm. in diameter. Vessels vari- 

 able in size, ranging from 0.072 mm. to 0.18 mm. in diameter, usually 

 two large vessels and either none or several small vessels on the side 

 away from the bast in each bundle. The phloem portion in general 

 destroyed and represented by a disorganized cavity between the ves- 

 sels and the bast. 



The ground mass of the stem consists of thin walled parenchyma 

 without intercellular spaces. The cells are small, isodiametric, 

 rounded pentagonal or hexagonal except where there are but one or 

 two rows between closely adjacent bundles, in which case they are 



