22 
PALEONTOLOGY OF NEW YORK. 
This species closely resembles C. venusta of this formation, but may be dis¬ 
tinguished as follows: The branches of that species are hollow, the cell aper¬ 
tures are slightly larger, more decidedly oval, often regularly arranged in quin¬ 
cunx over a large portion of the specimen ; but there are occasional^ specimens 
which could not be separated by the surface characters alone. 
Formation and locality. In the shaly limestone of the Lower Helderberg 
group, near Clarksville, N. Y. 
Callopora perelegans. 
PLATE XII, FIGS. 10-17; and PLATE XXIII A, FIG. 14. 
Callopora perelegans. Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 102. 1874. 
“ “ “ Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 154. 1879. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 12, tigs. 10-17. 1883. 
Zoarium fruticose, several stems arising from a common base; bifurcations 
very frequent. Branches solid, diameter from 2 to 5 mm., generally from 3 
to 4 mm. Cells tubular, arising from the center of the branch, gradually 
diverging till within one mm. of the surface, when they abruptly turn out¬ 
ward ; walls very thin. Septa infrequent or entirely wanting. Apertures 
circular or sub-polygonal from pressure, diameter .50 mm.; irregularly dis¬ 
posed, sometimes in contact; at other times distant one mm. or more : mar¬ 
gins thin, distinctly and equally elevated. Mesopores frequently longer than 
wide, length sometimes four times the width : margins equal in thickness 
and height to those of the apertures. Intercellular space occupied by septate 
tubuli of varying lengths, occasionally extending to the center of the branch. 
Septa very thin and frequent, from eight to twelve in the space of one mm. 
This species closely resembles C. elegantula of the Niagara group, and may be 
only a variety of that species. Externally the mesopores of C. elegantula are 
much smaller, and the width is usually about equal to the length. Internally 
the cell-tubes have numerous septa nearly equal in thickness to the cell-walls, 
frequently four in the space of one mm., while in this species the septae are 
very infrequent or entirely wanting. 
Formation and locality. In the shaly limestone of the Lower Helderberg 
group, near Clarksville, Albany county, N. Y. 
