GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 25 



narrowly compressed and elongated parallel to the sides of the 

 bundles. Their diameter varies from 0.035 mm. to 0.10 mm. Scat- 

 tered through the stem parenchyma are darker cells which in polar- 

 ized light appear to be gum cells. They are slightly larger than the 

 parenchyma cells, being from 0.072 mm. to 0.108 mm. in diameter. 



Occasional bundles are seen to be branching. These are the fas- 

 ciculi fibroductores or Kreuzungsbiindel. 



This species was first recognized by Sprengel in 1828, who referred 

 it to Endogenites; Cotta four years later transferred it to Fasciculites, 

 and Corda in 1845 referred it to Palmacites. When Felix came to 

 publish on the Antigua woods in 1883 he recognized this species, 

 but in describing it under the genus Pdlmoxylon which had been 

 proposed by Schenk only a year or two before he took the liberty 

 of giving it the new name of teneimm, which under the rules of 

 nomenclature has no standing as Stenzel recognized in print in 1904. 



The specimen from Panama is small and may be from near the 

 periphery of a stem, although in the group Lunaria there is little 

 difference between the central and peripheral regions. In the size, 

 outline, and crowding of the fibrovascular bundles as well as in the 

 character of the parenchyma of the groundmass the present species 

 greatly resembles Pdlmoxylon integrum described by Felix 1 from 

 Cuba and considered by Stenzel 2 as merely a variety of the Antiguan 

 species Pdlmoxylon antigu&nse (Unger) Felix. 3 It differs from that 

 species in altogether lacking the numerous auxiliary sclerenchyma 

 bundles which are so well marked in Pdlmoxylon integimm. A fur- 

 ther difference is the presence of gum or mucilage cells which are 

 fairly numerous in the Panama specimen of Pdlmoxylon palmacites 

 and which might upon a merely superficial examination be mistaken 

 for auxiliary sclerenchyma bundles. Among the Oligocene species 

 of Pdlmoxylon from the southern United States Pdlmoxylon missis- 

 sippense Stenzel * is very similar to the present species. 



Other described fossil species which show more or less resem- 

 blances are Pdlmoxylon stellatum, asckersoni, variabile, and ceylani- 

 cum. The nearest affinity among recent palms is not determinable 

 in the present state of our knowledge of the anatomy of the latter. 

 The present type of structure is commonly known as the Cocos- 

 like type. 



For some unknown reason the upper Eocene and lower Oligocene 

 in southeastern North xlmerica abounds in silicified palm wood. 

 Palm leaves are often very abundant in the Wilcox and Claiborne 

 Eocene and in the Apalachicola Oligocene; but all of the petrified 



* Felix, Foss. Holz. Westindiens, p. 24, pi. 5, fig. 2, 1883. 



2 Stenzel, Foss. Palmenholzer, p. 154, pi. 1, figs. 1-10, 1904. 



3 Felix, Foss. Holz. Westindiens, p. 22, pi. 4, fig. 5. 



* Stenzel, Foss. Palmenholzer, p. 248, pi. 21, figs. 254-265. 



