496 



NEW YORK STATE MUSEUM 



possess an acute and high ventral (outer) and a lower and narrower 

 dorsal saddle. The septa are moderately concave, their depth being 

 twice that of the cameras. 



The siphuncle is small, slightly nummuloidal, marginal at the 

 ventral side and in contact with the ventral wall. The composition 

 of the siphuncular wall has not been seen. 



The outer surface is smooth. 



Position and locality. Very rare in the bed of bluish-gray 

 crystalline Beekmantown limestone (D) below the lower Ophileta 

 bed at Beekmantown N. Y. 



Observations. The strongly compressed form of the conch, 

 the close arrangement and the rapid rising of the septa on the ven- 

 tral side and the marginal ventral position of the siphuncle leave 

 little doubt that this form is an Ooceras or belongs to a closely 

 related genus. 



Ooceras (?) raei Whitfield (sp.) 



Cyrtoceras raei Whitfield. Am. Mus. Nat. Hist. Bui. 1889. 2:58, 

 pi. 10, fig. 8, 9 



All that we know of this species which is based on a single frag- 

 ment collected by Professor Seely at Beekmantown is contained in 

 the original description, since no additional material has been 

 obtained. 



The fragment exhibits a short ventral portion only and fails to 

 furnish sufficient data for satisfactory generic reference. All that 

 can be said is that the form possessed a cyrtoceracone with depressed 

 section, low annulations or undulations of the outer shell, rather 

 shallow chambers (3^ in the space of 10 mm in the specimen), 

 sutures with a distinct ventral saddle, and a subventran marginal 

 siphuncle, which is nummuloidal. 



The rate of growth of the conch, the characters of the living 

 chamber and of the aperture, of the dorsal side and apical portion 

 and those of the surface of the conch are not known and presuppose 

 the discovery of new material for their elucidation. 



Ooceras seelyi sp. nov. 



Plate 38, figure 7-11 



Description. Small, breviconic cyrtoceracone. Length of 

 largest fragment 40 mm ; indicating that the complete specimen pos- 

 sessed at least the double length. The rate of growth of the form 

 is very great, one conch expanding from 1 5 to 29 mm within 32 mm ; 



