PALEONTOLOGY OF NEW YORK. 



Siphuncle near the concavo-ventrul side, having a diameter at the septa of 

 two nun., where the tube has a diameter of twenty-five mm. Its other 

 characters not observed. 



Test and surface-markings unknown. 



A small individual, nearly entire, has a length of sixty mm., with a greatest 

 lateral diameter of twenty-three mm., and preserves the chamber of habita- 

 tion and about fifteen air-chambers. Other larger examples have been 

 observed, but in a fragmentary condition. 



This species, in its peculiar curvature and size, resembles G. Conradi, of the 

 Hamilton group ; but the point of greatest transverse section is different, the 

 aperture smaller, and the tube more rapidly contracting toward the aperture. 

 It is distinguished from G. fax by the position of the point of greatest trans- 

 verse section, the endogastric curvature and apical angle. 



Formation and locality. Schoharie grit, Helderberg mountains, Albany 

 county, N. Y. 



GOMPHOCERAS ABSENS. 



PLATE XLVI, FIGS. 8, », and Supplement. 



Cyrttxxras absent, Hall. Illustrations of Devonian Fossils : Cephalopoda, pi. 47, figs. 7, 8. 1876. 



Shell small, arcuate, exogastric. Transverse section elliptical ; lateral diam- 

 eter the longer. The ratio of the ventro-dorsal diameter to the lateral 

 diameter is about as 3 to 4. Point of greatest gibbosity on the chamber of 

 habitation, near the last septum. Apical angle about 20°. 



Chamber of habitation bursiform, having a length equal to the greatest 

 lateral diameter of the tube. Dorsal side nearly straight, sometimes slightly 

 concave. Ventral side convex, and sloping rapidly to near the aperture, 

 where there is a sudden constriction of the tube, which is cylindrical from 

 this point to the aperture. Crenulated zone very narrow, but marki-d by 

 broad, shallow, transverse furrows. 



Aperture oval, with a width nearly ecpjal to the length of the grand 

 chamber. The small aperture is formed by a very small and shallow bend, or 



