No. 89.] 



97 



GONIATITES EXPANSES. 



Fia. 1. Lateral view of a young, or fpecimen of medium size. The surface marking ia shown 

 upon a part of the figure, while the outer cham*)er is left plain : s, the septa; o, 

 line parallel to the aperture. This is of the type of G. expansus (VANtrxEii). 



Fio. 2. Dorsal riew of fig. 1, showing the grooves and carina on the dorso-lateral angles. 



Geological formation and locality. In the Goniatite limestone of Marcellus, 

 Manlius, and near Schoharie, New-York. 



There is a fine collection of specimens of this species in the State Cabinet, in part 

 purchased of Mr. Gebhard; and a greater number, particularly of large indivi- 

 duals, presented by Ledyard Lixcklaex, esq., of Cazenovia. 



GONIATITES DISCOIDEUS ( n. s.). 

 Shell orbicular : volutions all embraced within the outer one; aperture subellip- 



tical, narrower anteriorly, widening towards the base, and slightly auriculate 



at its junction with the axis; sides convex, gently curving towards the back, 



and rounded upon the periphery. 



A specimen, which is apparently an adult, measures from the umbilicus to the 

 periphery one and one-eighth inches; across the volution at the ventral side, not 

 including the expansion of the mouth, five-eighths of an inch; and across the volu- 

 tion at the back, three-eighths of an inch. Another specimen, smaller but a little 

 more rotund, measures, at the same points respectively, five, three and two- 

 eighths of an inch. 



The septa are marked on the back by a short narrow lobe, and, thence extend- 

 ing laterally with a gentle curve halfway across the volution, bend suddenly 

 backwards, and make a sharp curve to the ventral side. They can scarcely be 

 described as lobed,aud the sinuosity approaches more the character of Clymenia. 



The surface is marked by fine undulating striae, which follow the direction of 

 the septa. 



Geological formation and locality. In the Goniatite limestone, at Manlius and 

 Schoharie. Specimens of similar form, and extremely compressed, occur in the 

 shales of the Hamilton group, at Cazenovia and elsewhere. They are probably 

 identical. 



The figure illustrates the form of the shell and the direction of the s$pta. 



[Senate, No. 89.J 13 



