328 PALM0S10L0QY OF SEW YOKE. 



GoMPHOCERAS ? CRUCIFERUM, 11. sp. 

 PLATE XCIU, FIG. 4. 



A specimen preserving a single septum with the walls of one air chamber has 

 been observed, which possesses an ornamentation unlike anything previously 

 noticed. It is placed in Gomphoceras on account of its association with 

 other species, and the amount of the curvature of the tube indicated by the 

 slope and direction of the chamber walls. 



Transverse section very broadly ovate, with the ventro-dorsal and the lat- 

 eral diameters nearly equal, — the narrower end toward the side containing 

 the siphuncle, which is apparently nearer the concave side of the tube, mak- 

 ing the curvature endogastric. 



Septa moderately concave. The septum shows an elevated, cruciform 

 ornamentation, with the intersection of the arms at the insertion of the 

 siphuncle, where there is a small areolar marking. The longer arm of the 

 cross is lanceolate, and extends toward the convexo-ventral margin, having 

 a length somewhat less than one-half the dorso-ventral diameter. It is sur- 

 rounded by indistinct concentric striae. The three shorter arms form a tri- 

 angular, trilobate expansion, with an ovoid elevation, surrounded by a furrow 

 on the central lobe. 



Siphuncle small on the concave side of the tube, having a diameter of two 

 mm. where the dorso-ventral diameter is forty-five mm., and distant from 

 the nearest margin of the septa about one-third the diameter of the tube. 



This species is distinguished by the remarkable ornamentation of the septa, 

 which is sufficient to separate it from any allied form. The evident curva- 

 ture of the tube and the transverse section remove this species from Ortho- 

 ceras, in which genus there are several species showing an ornamentation of 

 the septa. In 0. pravum the aspect of this feature is similar, but the details 

 are very different. 



Formation and locality. In the Schoharie grit, at Schoharie, N. Y. 



