OTICA SLATE AND HUDSON-RIVER GROUP. 369 



obtuse teeth, which are separated from each other by a narrow slit, and each one about 

 half as wide as the entire width of the fossil 5 the slit or serrature extends about half way 

 to the axis. The specimens all become gradually narrower towards the base, which presents 

 two diverging forks ; these are sometimes thickened or expanded, and in other cases very 

 slender, the serrae often continuing beyond the divergence. But for the direction of the 

 serrae, which are regarded as ascending, we might consider this bifurcation as the summit 

 or termination of the fossil. 



When imbedded in calcareous matter, this species has a thickness of about half its 

 width, with a prominent round midrib on one side, and the other is often flat or depressed. 

 The substance of the fossil, in such cases, appears to be calcareous or semicalcareoUs, 

 with a corticiferous covering, which is probably true of all the graptolites. The specimens 

 preserving their original form have the outer margins of the teeth concave, with the 

 upper and lower angles mucronate ; but this character is scarcely ever preserved when the 

 fossil is imbedded in slate. 



Fig. 2 a. A small specimen of the natural size, showing the bifurcation below. 



Fig. 2 6. A portion of the same magnified, showing the form of the teeth. 



Fig. 2 «. A larger specimen, having the same character with a stronger bifurcation, which is thickened 



at the point of separation. 

 Fig. 2 i. A portion magnified. 

 Fig. 2 «. A specimen having similar obtuse teeth, with the base removed and the midrib projecting 



above. 

 Fig. 2/ A fragment of slate, with several specimens preserving the peculiar radical termination, 



associated with Gf. ramosus. 

 Fig. 2 g, h. Magnified portions of these, showing a partly uniform character in the teeth. 

 Fig. 2 i. A fragment of this species in the slate, preserving its original form in a good degree. 

 Fig. 2 k. The same enlarged. 



Fig. 2 /. A fragment in limestone. 2 I'. A more compressed form in the same. 

 Fig. 2 m, m'. Enlarged portions of the same. 

 Fig. 2 «". A magnified view of the edge of a specimen in limestone showing an appearance analogous 



to G. scalaris. 

 Fig. 2 n. Transverse sections of the same magnified. 

 Fig. 2 0. A slender specimen, with the sides parallel. 



Fig. 2 p. A similar specimen, preserving the capillary axis beyond the remaining portion of the stipe. 

 Fig. 2 r, s. Magnified portions of these, showing their identity with the preceding. 



Position and locality. This species is among the most common in the slates near Albany, 

 and at Ballston, Saratoga county. It is more rarely seen in the slates in Columbia county, 

 and its occurrence in the Mohawk valley is doubtful. It occurs likewise at Cincinnati and 

 other western localities, and appears to be the most common species in that part of the 

 country. (State Collection.) 



