CORALS AND BRYOZOA. 
13 
reaching 5 mm.; diameter .20 mm.; apertures slightly oblique to the surface. 
Septa thin, infrequent. 
This species may be distinguished from C. abruptus [plate ix, figs. 9-11], 
by its fruticose appearance, its more slender growth, (which character appears 
to be constant), the thinner and more infrequent septa, but especially by the 
manner in which the cell tubes approach the surface. 
Formation and locality. Lower Helderberg group, Schoharie, N. Y. 
Ch^tetes (Monotrypella) abruptus. 
PLATE IX, FIGS. 9-11. 
CInBtetes abruptus, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 14S. 1S79. 
*■ “ “ Report of State Geologist for 1882. Expl. pi. 9, figs. 9-11. 1S88. 
Corallum ramose, solid; branches frequent, diverging at an angle of about 
forty-five degrees. Cells tubular, polygonal; arising from the center of the 
branch and very gradually diverging until about 2 mm. from the surface, 
when they abruptly turn outward. At this point they are generally con¬ 
stricted, and the cell walls, previously very thin, become much thicker; 
length reaching 6 mm.; diameter at the surface from .20 to .25 mm.; 
frequently spinulose at the angles. Septa rare or entirely wanting until 
after the abrupt turning of the cell tubes, when they are numerous. 
This species, when a longitudinal section can be seen, is easily recognized by 
the abrupt turning of the cell tubes to the surface, also in the constriction and 
thickening of the walls at this point, features in which it differs from any 
other species of this formation. 
Formation and locality. Lower Helderberg group, Schoharie, N. Y. 
