Barber. — Cnpressinoxylon vec tense. 343 
of small branches, as in the case of Goppert’s C. nodosum. 
See also his figure of a Larch-stem with many small lateral 
branches and wavy rings h 
The width of the rings of growth as defined above is 
somewhat variable. This character is not now regarded as 
of diagnostic value, since the rings will vary in width according 
to climate, age, soil, and the part of the plant. 
As the same ring differs considerably in different parts 
of its course, the measurements have been taken in all 
directions where the structure has been undisturbed. 
Branch (1). Average width of first ten rings 1*7 mm., 
varying from *6 mm. to 2-8 mm. 
Branch (2). Average width of first ten rings 1-45 mm., 
varying from -7 mm. to 2*3 mm. 
Root (x). Average width of first twelve rings 1-07 mm., 
varying from -4 mm. to 2-i mm. 
Root (2). The rings near the pith are quite indistinct. 
Then follow five rings with an average width of 1*7 mm., 
varying from 1 mm. to 3-4 mm. After this five narrow, dark 
bands occur at distances of from -2 mm. to -8 mm. 
Pith and Medullary Sheath. 
The pith has received careful examination whenever the 
sections have admitted. It is obvious that from its study 
great assistance might be expected in determining the root- 
or shoot-nature of organs. This expectation was only par- 
tially realized. In the first place the usual absence of pith 
from pieces of fossil wood has caused it to receive small 
attention in the literature of the subject, and secondly the 
state of preservation of the cell-wall did not allow the 
markings to be clearly seen at the critical points. The 
diameter of the pith in branch (1) and branch (2) was -9 mm. ; 
in root (1) it was -4 mm., and in root (2) -3 mm. This is 
in agreement with Nordlinger’s statement that, while in 
Goppert, 1. c., Tab. i ? Fig. io, 
A a 2 
