No. 89.] 



99 



GONIATITES ORBICELLA (ii.^O- 

 Shell small, depressed orbicular, without distinct umbilicus, the volutions deeply 

 embraced in the succeeding ones; aperture comparatively large. Dorsal lobe un- 

 known; dorso-lateral lobe narrow and deep, with a wider lateral saddle, and a 

 slight undulation towards the centre. 



The specimen is compressed, so that its original form is riot fully 

 known. It is readily distinguished from O. uniangulttris by the 

 undulations of the septa. 



GOKIATITES ORBICELLA. 



Geological formation and locality. 

 lowville. 



In shales of the Hamilton group; at Lud- 



GONIATITES PATERSONI Cn.s.). 



The spjcimen is a fragment, consisting of a part "of one of the outer volutions, 

 with some portions of the inner volutions still attached. This is a cast of about 

 two tnd a half inches in length : the distance from the centre or umbilicus to the 

 dorsal side, at the widest part, is one inch and five-eighths; the depth of the vo- 

 lution, from the dorsal to the ventral side, is one and a quarter inches; and the 

 greatest transverse diameter, at the commencement of the umbilical depression, 

 is seven-eighths of an inch, while the diameter near the dorsal edge is but threes- 

 eighths of an inch. The umbilicus has been moderately large; showing, however, 

 less than half the vertical diameter of the inner volutions, since the next within 

 the outer one of this fragment has nearly three-fourths embraced within the ven- 

 tral concavit)' of the latter. The dorsal lobe is angular, and scarcely pointed except 

 in the younger portions : the dorso-lateral lobe is extremely narrow and acute, 

 the septum rising in a narrow arch, and again descending to form a more obtusely 

 angular lateral lobe. 



This species shows a greater extreme in the sinuosities, or complexity of the 

 septa, than any other in the group at present known to me. 



GONIATITES PATEBSONi. 



Fig. 9. Afragment of tho natural size. Fia. 10. Diagram of the septa. 



Geological formation and locality » In shales of the IlamiHott gi'oup : at P«- 

 terson's creek, Livingston county, N.York. 



