278 
PALAEONTOLOGY OF NEW YORK. 
surfaces are covered by the zoarium. The cell tubes are sub-cylindrical, at 
first rapidly expanding, but for the greater portion of their length the mar¬ 
gins are parallel; transverse section oval in outline, length from 1.25 to 2 
mm., diameter .33 mm., generally arranged in alternating order, and often 
regularly distant, on the same side of the branch 1.50 mm.; the angle of 
divergence from the axial tube is sometimes equal to forty-five degrees, at other 
times they are in contact with the axis for nearly their entire length, turning 
abruptly outward near the end, the apertures being parallel with the axis of 
of the branch and a little constricted; during the process of growth the 
apertures are rectangular to the axis. Surface marked by numerous, strong, 
transverse striae, with finer striations between, and frequently the stronger 
striae have the appearance of prominent annulations; the cell tubes vary in 
their surface characters, some of them having only the prominent annula¬ 
tions, others only the fine striae, while still others have both the annulations 
and finer striations, and when well preserved they have also numerous, 
very fine longitudinal striae. 
This species is intermediate in size between Hederella cirrhosa and Hederella 
fdijormis; from the former it is easily distinguished by the greater size of the 
cell tubes and the coarser appearance of the frond; from the latter it may be 
distinguished by the smaller diameter and greater length of the cell tubes, the 
cells of that species being more than .50 mm. in diameter, and seldom having a 
length of more than 1.25 mm.; the frond of this species is also much less com¬ 
pact in appearance: from H. magna it is distinguished by the much smaller size 
of the cell tubes, those of that species having a diameter of more than 1 mm. 
Formation and locality. Hamilton group, York, Livingston county, N. Y. 
Hederella eiliformis. 
PLATE LXV, PIGS. 9-11. 
Aulopora fimformis, Billings. Canadian Journal, New Series, vol. 4, p. 119. 1S59. 
Hederella “ Hall. Trans. Albany Institute, vol. x, p. 194. 1881. 
“ “ “ Report of State Geologist for 1S83, p. 94. 1884. 
Zoarium parasitic, procumbent, attached for its entire length, consisting of an 
elongated, sub-cylindrical primary axis, from which proceed, laterally, simple 
