■33fi The American Geologixf. ■ Dircmhii, \^\k 
cover jilass springs buck to its noniuii position and in so doing 
trnds to (Inivv away from tlio jelly immediately bolovv. The 
necessary consequence of tliis is the formation of a cavity which, 
owing to the peculiar consistency of the jelly, will assume the 
form of :i series of irregularly branching nunuli often dispersed 
in a stellate manner. The figures and tubes thus formed are in 
all essential respects the exact counterpart of the rainuli found 
in tile rods of cannel ct)al now under consideration, and 1 think 
we may safely infer that the latter arise from the same general 
•cause as the former. This would make them the result of inter- 
iKil shrinkage caused 1)\- the graduiil elimination of a volatile ele- 
ment, but as the loss of such a volatile constituent must always 
take place Ri-st at the surface, there would necessarily be formed 
a-n external layer of greater resistance which would tend to pre- 
serve the originid form and promote a shrinkage through the 
central mass towjirds the firmer bounding layer. This view is also 
justified by the known occurrence of similar shrinkage cracks 
and pockets in amber and other forms of fossil resin. 
The material oecupying the spaces between the rods and ap- 
l)arently ct'menting them together, consists of an amorphous and 
irregularly granular mass full of rounded holes, thereby giving it 
a spongy character. Within this matrix are imbedded numerous 
small, angular or rounded — sometimes laminte — -fragments of 
material which, from its general aspects, appears to be the same 
as the rods, and in all proba])ility is the material of rods which 
were l»roken up in various ways. The presence of such frag- 
ments and the curious way in which the rods are massed in thick 
seams, together with the absence of other material, would seem 
to indicate tiie agency of water. The source of the amorphous 
substance is not so clear. It has no apparent relationship with 
the rods and fragments, nor does it anywhere i)resent any struct- 
ural aspects, so that we are left wholly in doubt as to its possi- 
ble nature. A hypothetical view might regard it as the debris of 
vegetable structure, but it does not appear so carbonaceous as 
material from such a source should l)e. 
These considerations render it fairly clear that the origin of 
these coals nuist lie sought in some other direction than modified 
vegetable structuri'. From their character as determined Ity mi- 
croscopical examination, from their fracture and color in trans- 
mitted liiiht. as well as from their comtaistible nature, we can 
