NIAGARA GROUP. 173 
solid space where no cells appear ; and it often happens that some other species of coral has 
commenced growth upon this species, as in the example figured. 
Fig. 6 a. A fragment of an Orthoceras covered by this coral, showing at two points a', a", the 
growth of other corals upon this one. 
Fig. 6 b. An enlarged portion of the surface, showing the form and arrangement of the cells in 
this species, and in a species of Callopora which covers it in parts. 
Position and locality. This coral occurs attached to Orthocerata in the shale at Rochester, 
Marshall’s mill, and Lockport. 
PLATE XL E. Fig. 7 a, b. 
An incrusting coral enveloping a Stephanocrinus. The form of the shallow cells is different 
from any mature species yet observed in this rock ; and probably it is only the commencement 
of growth of a coral or bryozoa, which, in a perfect or mature condition, presents a different 
character. Should it prove to be a mature form, it will find its analogues in the Flustra or 
Eschara type. 
Fig. 7 a. The coral enveloping a broken crinoid. 
Fig. 7 b. An enlargement of a portion of the surface. 
Position and locality. In the shale at Lockport 
PLATE XL E. Fig. 8 a, b. 
An incrusting membrano-calcareous coral, growing upon Lichenalia and other bodies. 
Coral composed of tubular cells, which increase by regular dichotomizing, transversely striate 
or rugose ; a nearly circular aperture of each simple tube, opening upward, at the point where 
bifurcation takes place. 
This species is very peculiar and characteristic, probably forming the type of a distinct genus. 
Its mode of growth is somewhat like Aulopora, but the tubes are more minute, closely ad¬ 
hering to the body to which it is attached, and placed laterally in juxtaposition. The frequent 
bifurcation of these tubes causes a rapid expansion of the coral, and it spreads in nearly circular 
or flabellate blotches. 
Fig. 8 a. A portion of Lichenalia, on which this coral is growing. 
Fig. 8 b. An enlargement showing mode of growth and character of tubes. 
Position and locality. In the shale at Lockport, growing upon Lichenalia and other corals. 
