Sil6 PALEONTOLOGY OF NEW- YORK. 



\ive form in that epoch. The species has a wide geographical range, being known 

 ^roiighout New-York, Canada West, Ohio, in tho Mississippi valley, and as far 

 aouth !is Virginia. 



The S.JinAriata is the first of this type in our formations, but is represented 

 by similar forms* to the close of the Carboniferous period. 



In the illastrations of those Bpecies, the fragment 1 is from the Oriskany sandstone 

 the figures 2, 3 and 4 are from the Schoharie grit ; figures 5-11 are from the 

 Corniferoufi limestone : the remaining figures are from the Hamilton group. 



Geological formation and locality. This species occurs in the Oriskany sand- 

 stone at Saugerties in Ulster county, and at Knox in Albany county, and probably 

 in Schoharie. It is found in the Schoharie grit in All)any and Schoharie counties, 

 and in the Comiferous limestone in the same region ; and at Cherry-valley ; 

 Westmoreland, Oneida county ; Onondjiga-hoUow, Onondaga county ; Stafford, 

 Qencsee county ; Williamsville, Clarance, and other places in Erie county ; in 

 Canada West, and at Columbus and other places in Ohio. 



In the Hamilton group, it occurs on the shores of Seneca and Cayuga lakes, 

 and upon Canandaigua lake ; at York and Moscow in the Genesee valley ; and at 

 Darien; at Eighteen-mile creek, and other places in Erie county. Also in the same 

 group in Maryland and Virginia ; and at Davenport and New-Buffalo, Iowa ; ai 

 ^ck-islaud, Illiuois ; ^nd elsewhere in the Mississippi valley. 



Spirifera mucronata. 



PLATE XXXIV. 



Delthyrit mueronala : Cohrad, Ann. Report on the Geology of New-York. 



" " Vanuxem, Geol. Report Third District, p. 150. 1842. 



" " Hall, Geol. Report Fourth District, p. 198. 1843. 



Spir}fera mucronata : Bilungs, Canadian Journal, May, 1861. 



Shell more or less gibbous, semicircular, semioval, or triangular in out- 

 line ; cardinal angles sometimes truncate but usually extended, and 

 often extremely prolonged into mucronate points, giving a length of 

 hinge-line two, three or four times as great as the shell ; sides straight 

 or curviag, the front straight or concave. 



Ventral valve often scarcely more convex than the dorsal, but in very 

 gibbous forms becoming more unequal, gently curving to the lateral 

 margins. The beak is small, and incurved over the narrow linear area, 

 the mesial sinus is sharply defined quite to the apex, and limited by 

 angular plications which are stronger than the adjacent ones. The 



• 8. pteudolintata and 8. leligtra, see Geology of Iowa, pp. 645 and 705. 



