CEPHALOPODA. 
281 
can only be verified by a critical examination of numerous individuals in all 
conditions of preservation, and from sections made with a view of ascertaining 
the extent and position of the organic deposit. 
This species, so far as known, is confined within the limits of the Goniatite 
limestone in the Marcellus shales, and is the “ Marcellus orthocera” of Vanuxem 
{Report of the Third District, p. 149: 1842), and mentioned on p. 147 of his 
report as “ a large Orthocera, the Marcellus .” Dr. Saemann cites Cazenovia, 
Madison county, N. Y , as the original locality for his species. This is 
an evident error in the locality reference; but there is no doubt as to the 
present identification, as he describes this species, the formation, and its 
association with Goniatites, Gomphoceras, etc. 
Formation and localities. In the Goniatite limestone of the Marcellus shale, 
at Manlius, Marcellus, and other localities in the central portion of the State. 
Orthoceras fustis, n. sp. 
PLATES LXXXIII, FIG. 11 ; CXIII, FIGS. IS, 17. 
Shell straight, very regularly and gradually enlarging to near the aperture. 
Transverse section circular. Apical angle 4|°. Initial point unknown. 
Chamber of habitation short, having a length of about twice the diameter 
at the last septum, with several obscure undulations throughout the length, 
except the one near the aperture, which is a very distinct and abrupt 
constriction following the sinuosities of the margin. Aperture abruptly con¬ 
tracted, with two or three broad sinuosities in the margin. Air-chambers 
regular, numerous, having a depth of five mm. near the grand chamber, 
where the diameter of the tube is thirty-five mm. 
Septa thin, smooth near the outer chamber, having a concavity equal to 
an arc of nearly 90°. Sutures straight and horizontal. 
Siphuncle central, straight, nearly cylindrical, abruptly constricted in its 
passage through the septa, where it has a diameter equal to about two-thirds 
as great as in the air-chambers. Its diameter is 3.5 mm. where the tube 
has a diameter of about thirty-five mm. 
36 
