[PENHALLOW] NOTES ON FOSSIL WOODS FROM TEXAS 97 
gled. Thyloses in the vessels numerous, large, thin-walled. All other 
structural details obliterated. 
Tangential—Medullary rays of two kinds:—(1), 1-seriate rays upwards of 
twelve cells high; the cells all thin-walled, oblong cr rectangular, 
uniform but unequal; (2), multiseriate rays composed of 3-5 rows 
of high, thin-walled, very unequal and very variable cells which often 
become 1-seriate and much larger at one or both extremities of the 
ray. Vessels bearing numerous thin-walled thyloses, and upon their 
radial walls, numerous hexagonal, bordered pits which occupy the 
entire area of the wall. 
Specimens highly silicified and the structure showing an advanced 
alteration through decay. 
It would appear, however, that the flora of the Somerville clays 
embraces a wider representation of the Rhamnaceæ than is indicated, by 
the foregoing, since it has been possible to identify at least one species 
of Reynosia which appears to present a somewhat striking approximation 
to the existing R. latifolia of Florida, the Bahamas and Cuba. 
REYNOSIA TEXANA, 0. SP. 
Figs. 4-5. 
\ 
Transverse—Growth rings narrow and poorly defined, with no obvious dis- 
tinction between spring and summer woods, but the outer limits of the 
ring are generally marked by the presence of more or less numerous, 
radially flattened and tangentially extended wood cells which form a 
disconnected zone, upwards of four cells thick. Wood cells small, 
very unequal, about 14 « broad, hexagonal in irregular radial rows, 
the wall very thick, the cavity reduced to about 2.63 yw. Vessels 
rather numerous throughout, very resinous and thick-walled, round 
or oval, single or radially 2-seriate, at first relatively large but toward 
the outer limits of the ring somewhat abruptly reduced to one-half 
size; often enclosed more or less completely by an irregular layer of 
rather larger and thinner walled wood parenchyma. Medullary rays 
numerous, prominent, somewhat resinous, 2 cells wide, distant up- 
wards of 12 rows of wood cells. 
Radial.—Medullary rays resinous with cells of two kinds:—(1), the marginal 
cells high, short, in 1-3 rows; the upper, lower and terminal walls 
finely but strongly pitted; pits on the lateral walls are recognizable; 
(2), thinner walled cells forming the central region of the ray, fusi- 
form, but the pits not recognizable on any of the walls. Vessels with 
short, thick-walled and strongly pitted thyloses, forming a conter- 
minous series; very resinous, the resin localized in masses which fill 
the cavity. 
Tangential. Medullary rays all of one kind, 2-3, rarely 1-seriate, the breadth 
varying much, according to the size of the component cells; fusi- 
