234 
PALAEONTOLOGY OF NEW YORE. 
Test about one mm. thick, preserved in very few of the numerous indi¬ 
viduals observed. Surface marked by irregular, lamellose strise of growth. 
Some of the specimens referred to this species have been more than sixty 
centimetres in length. The diameter of the tube towards the aperture in 
the larger specimens is from sixty to one hundred mm. In all the speci¬ 
mens examined, the interior is filled with the same material as the surround¬ 
ing rock. The septa are often partially destroyed, broken or distorted, and 
the siphuncle, as shown in figs. 2, 4, of plate 35 A, is very imperfectly pre¬ 
served, showing no decisive characters in sections thus far made, or any 
evidence of an organic deposition. The specimen, fig. 1, pi. 35 A, has a 
length of thirty-five centimetres, and is imperfect at both extremities (a part 
only being figured). 
This species is scarcely known except in the condition of casts of the interior, 
of which specimens are rarely found having a length of sixty centimetres, but 
are always imperfect. In the ordinary conditions of preservation, where the 
specimens are more or less compressed, and imbedded in a coarse grit, it is 
impracticable to recognize the less conspicuous differences of character between 
this and other species, the most marked feature being the larger size and 
greater distance of the septa in this, as compared with other similar forms in 
the same rock, except 0. masculum, in which the distance between the septa is 
so much greater as to be readily distinguished. From 0. Zeus, this species is 
distinguished by its smaller apical angle and lesser convexity of the septa; 
the other characters are not unlike. This form bears some degree of external 
resemblance to a species in the Hamilton group (0. Eriense), but the internal 
characters are quite distinctive. 
In its vertical range it is confined, so far as known, to the Schoharie grit, 
the variety formerly designated as 0. Ohioense, from the Upper Ilelderberg 
limestone of Ohio, proving a very distinct species. 
Several large, imperfect individuals have been observed among collections 
made from the Upper Ilelderberg limestone of Cherry Valley, N. Y., of Ohio, 
and Ontario, Canada, which possess characters in common with 0. Pelops. The 
apical angle is about 7°. Air-chambers slightly irregular in depth, varying 
