APPENDIX. 339 
most likely view is, that some preservative matter from without found its way readily through 
the ducts, and spread into the surrounding wood, and quite through the cells of the medullary 
rays. The brown color deepest in the cavity of the ducts, and fading gradually at a little dis- 
tance from them, confirms this view. 
Radial section —In this view the medullary rays are seen composed of uniform cells of small 
size, closely covering the walls of the ducts where structure cannot be made out. Very few 
wood cells can be distinctly seen. 
The tangential section shows an end view of the rays, composed of fifteen to twenty and some- 
times twenty-five cells, lengthwise, and three in width, as before stated, not in the same hori- 
zontal plane. In this view the small size and closeness of the cells bent round the ducts give 
at the first glance the appearance of annular or spiral vessels, but a closer examination reveals 
the true structure. The wood is, therefore, that of an exogen, and is not coniferous, and must 
be comparatively modern. 
It is to be regretted that the structure of the ducts could not be clearly made out, but from 
the description it can be easily ascertained what it should be. 
The presence of wood parenchyma could not be determined. These characters will easily 
enable us to determine this wood in specimens less altered, from which the relations to existing 
wood can be better determined. There is a close resemblance to a fossil wood from Antigua, 
figured in Witham ; this last, however, is unaltered. 
EXPLANATION OF THE FIGURES. 
Plate XII, Fig. 3.—Transverse section of fossil wood from the Colorado Desert; magnified 100 times 
ig. 4. Tangential section ; more highly magnified. The cells of the medullary rays seem to be slightly separated ; but 
this results from the view being somewhat iat: the direction of the rays ES: so much that it is difficult to obtain 
a section strictly perpendicular more than one series. 
