234 PALEONTOLOGY OF NEW FORK. 



Test about one mm. thick, preserved in very few of the numerous indi- 

 viduals observed. Surface marked by irregular, lamellose striae 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 O. Ohioense, from the Upper Helderberg 

 limestone of Ohio, proving a very distinct species. 



Several large, imperfect individuals have been observed among collections 

 made from the Upper Helderberg 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 



