252 
PALAEONTOLOGY OF NEW YORK. 
show an organic deposit. It is closely allied to 0. collatum , and may be 
distinguished by its more distant septa and their greater concavity. The speci¬ 
mens do not preserve enough of the chamber of habitation to admit of 
comparisons with 0. collatum in this particular. 
Formation and localities. In the Schoharie grit at Schoharie, and in the 
Helderberg range. 
Oethoceras collatum, n. sp. 
PLATE LXXX, FIGS. 1, 3, 4. 
Shell straight, regularly and gradually enlarging from the apex to a point near 
the aperture. Transverse section subcircular, often much flattened from 
compression. Apical angle varying from 4° to 6° in the specimens. Initial 
point unknown. 
Chamber of habitation large, slightly expanding beyond the general 
enlargement of the tube, to a point anterior to the middle, where it is 
abruptly constricted. In front of the constriction the tube expands gradu¬ 
ally towards the aperture. Aperture not observed. Air-chambers regular, 
having a depth of about eleven mm.; walls flat and smooth. The ventral 
side is indicated by a low, longitudinal carina on the chamber walls, which 
is more prominent on the anterior portion. This line is shown on the casts 
of the interior, and has a width of about one mm. 
Siphuncle large, slightly excentric, having a diameter at the septa of 
nearly four mm. Its elements in its passage through the chambers have 
not been observed. 
The characters of the test and its ornamentation are not shown on any of 
the specimens at hand. It was probably thin and has been dissolved, leav¬ 
ing a cast of the interior. 
The internal mould is essentially smooth. The ventral carina and the 
marked constriction of the chamber of habitation are the only distinctive 
features. 
