BIRDSEYE LIMESTONE. 
37 
BIRDSEYE LIMESTONE. 
FOSSIL PLANTS? OF THE BIRDSEYE LIMESTONE. 
Plates VIII. & IX. 
The Birdseye limestone is well developed along the valley of the Mohawk river; and 
in many places, owing to the absence of the Chazy limestone just mentioned, it succeeds 
directly to the Calciferous sandstone. It is distinguished by its thick layers, evenly bedded 
structure, and well marked vertical joints, which give the rock, when quarried, the ap¬ 
pearance of a wall. It is usually of a bluish grey or light dove color, weathering to a light 
ashen grey : in its western extension it loses its bluish shade, becoming lighter in color. 
The rock is fine-grained or compact, breaking with a conchoidal fracture, the surface 
presenting numerous crystalline points or spots. 
The organic remains of this rock are not numerous in species ; but their existence, though 
often very obscure, has given it a lithological character, by which it is known over a wide 
extent of country, and from which its name has been derived. The peculiar forms described 
in the succeeding pages (Plates VIII. & IX.) enter largely into the rock, and in many 
places constitute no small portion of the whole mass. They are frequently partially 
obliterated by crystallization ; but in far the greater number of instances, a weathered 
surface exhibits them in greater or less perfection ; and although the species are so few, 
there is no rock better characterized than this one by its palaeozoic features. The form and 
mode of growth are such as to distinguish these fossils from all preceding or succeeding 
forms; and though a single stem may resemble other marine vegetation, yet, when taken 
in combination, they present features totally distinct and unique. In the most prominent 
species, the stems are vertical to the strata ; and they are, as it were, tied together at 
intervals throughout their whole extent, by diverging branches which unite with the 
contiguous stems on all sides. In this respect, they present a feature unknown in either 
the corals or marine plants of the Fucus family. Their internal structure also presents some 
similar anomalies ; for while we find in some parts a structure like the cellular tissue of 
ordinary plants, we find, in others, cells or tubes bearing some analogy to the zoophytes. 
The substance also appears to have been partially calcareous or corticiferous, at least the 
external coat. In order, therefore, to give some expression to this apparent combination of 
structure, if such it prove to be, I have proposed a distinct generic name, to include at least 
two well-marked species. 
