E.rdiHiiHifion <]f So-c(dled Caruiel Coal. — Pi'iiJiaJhur. 337 
only conclude that they represent some form of fossil resin. The 
possibility of their derivation from resin was first suggested by 
Dr. (t. M. Dawson in his fii-st letter transmitting the specimens. 
But certain difficulties seem to stand in the way of this hypothe- 
sis. Among these is the absence of any lines of How. We may, 
however, conceive the resin to have been solidified in the resin 
passages of the tree, and this is certainly implied by the form and 
size of the rods as now found. 
Again, the enormous volume of these rods, sufficient to pro- 
duce thick and extensive coal beds, would almost seem to be in- 
compatible with their (n'igin in the way suggested above, unless 
we suppose (a) that the resin bearing trees of that period were 
enormousl}' abundant — far exceeding anything known in modern 
vegetation, and possi))ly of a species which has ceased to exist, 
or (b) that the trees produced resin in such enormous quantit}' 
that rapid and great accumulations were possiljle. 
The complete absence of any definite structure associated with 
the specimens, still further complicates the problem, though it is 
quite possible that the plant remains found in the surrounding 
strata may throw important light upon the subject, whim oppor- 
tunity offers to systematically collect and study them. In the 
present state of our information, three possibilities suggest them- 
selves. (1) The resin was produced wholly in the bark. Upon 
decay of the trees the bark separated from the wood, the two 
floated independently and may have eventually reached the same 
or different places of deposit. The free bark while floating suffered 
sufficient disintegration to lil)erate the contained resin, which was 
carried to a separate place of deposit. This hyjjothesis gains no 
support from modern vegetation. and is tloubtlessone which will fail 
to satisfactorily account for the great accumulations found. (2) 
The occurrence of the resin in the wood or in both wood and bark, 
the structure of which decayed sufficiently to liberate it after l)eing 
hardened. In such case we might reasonabh' expect to find some 
remnant of the woody structure associated with the rods. Their 
purity, however, indicates a complete separation from the structure 
in which they had tiieir origin,and, moreover, such separation must 
have taken place with great facility. Modern examples lend no 
support to this view. (3) The resin tubes may have been pro- 
duced in layers in such a way as to promote a rapid and complete 
breaking \\\) of the (ji'ganic sti'uctuie in drying or decay, with 
