326 P - 1 LMO S TOLOG Y OF NE\ V 10 II A ". 



GoMPHOCERAS BETA. 



PLATE XI.VI, PIGS. 4, S. 



Ooaphocertu beta. Hall. Descriptions of New Species of Fossils, p. 44. 1861. 



Fifteenth Rep. N. Y. State Cab. Nut. Hist., p. 72. pi. 7, Rg. 1. 1862. 

 •• " " Illii.-tratinns of Devonian Fossils: Cephalopoda, pi. 47, figs. 5, 6. 1876. 



Shell small, gibbous, nearly straight ; exogastric. Ventral side more convex 

 tban the dorsal. Transverse section elliptical. Longitudinal section sub- 

 oval, with the greatest transverse diameter through the second or third sep- 

 tum back of the grand chamber. Tube rapidly enlarging from the cipex to 

 the point of greatest transverse section, and contracting rapidly to the aper- 

 ture. Apical angle, in a compressed specimen, about 47°. Apex acute. 



Chamber of habitation large, with a length equal to the diameter of the 

 tube at the last septum, or more than one-third the entire length of the shell. 

 The ventral side is the more convex, and slopes more rapidly to the aperture 

 than the dorsal side. Crenulations distinct, traces of them showing on the 

 cast of the walls of the air-chambers. 



Aperture small ; its other characters have not been satisfactorily observed. 



Air-chambers regular, comparatively deep, having a depth of more than 

 three mm., and showing but a slight decrease toward the apex. 



Septa smooth, thin, with a concavity equal to the depth of the air-cham- 

 bers. Sutures horizontal, slightly curving, impressed upon the cast. 



Siphuncle moniliform, very near the ventrum, sometimes exposed in the 

 process of weathering. 



Test and surface-markings unknown. 



One example shows the chamber of habitation with seven air chambers, 

 and has a length of thirty-six mm. When entire, it probably had a length 

 of about forty-five mm. 



This species is distinguished from the associated forms by its short gibbous 

 shell, rapidly tapering toward both extremities. It is less globose than G. 

 oviforme, of the Hamilton group, and the point of greatest transverse section is 

 different. 



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



