156 
ON TRIGONOCARPONS CONTAINED IN NODULES OF LIMESTONE. 
from those existing at the present time, that it becomes dangerous to speculate upon 
them. 
On Plate V. are four highly magnified views of the tissues in the limestone matrix 
surrounding the Trigonocarpom : these appear to belong to very different groups of 
vegetables, and being a very small proportion of the variety that does exist, lead to 
the conclusion that the flora of the period was a varied and profuse one. We have 
few remarks to offer upon them. Fig. 1 represents a tissue resembling that of 
Dadoxylon. Fig. 2 probably belongs to a plant allied to the Ferns. Fig. 3, appa- 
rently an exogenous wood, crossed by medullary rays. Fig. 4 is also a Fern. 
