UTICA SLATE AND HUDSON-RIVER GROUP. 
271 
326. 7. GRAPTOLITHUS SCALARIS. 
Pl. LXXIII. Figs. 4 a- g. 
Graptolithus scalaris. Linne. 
Prionotus scalaris. Hisinger, Leth. Suecica, Supplement, 1837, pag. 115, pl. 35, fig. 4 ah. 
Linear, straight, rigid, compressed, with a capillary central axis ; margins smooth ; spaces 
on each side of the axis marked by transverse slits or dissepiments, which do not reach the 
margin ; stipe narrowing towards the base, and terminating in a thickened expansion. 
This appears to be identical with the figure tmd description of Hisinger. I have other 
specimens which show no central axis, and have but a single range of transverse dissepi¬ 
ments ; these I have arranged with the former, believing that this difference is due to 
accidental causes, or to one side of the specimen only being shown. 
This species is more rigid than either of the preceding, except G. bicornis , and is readily 
distinguished by the absence of serratures on either margin. 
Fig. 4 a. A specimen showing the radical termination. 
Fig. 4 b. A portion of the same magnified. 
Fig. 4 c. A more slender and tapering specimen, with a single range of dissepiments. 
Fig. 4 d. A portion of the same magnified. 
Fig. 4 e,/ A small fragment, with oblique dissepiments and smooth margins. This resembles the G. 
Sagittarius , with both margins uninterrupted. 
Fig. 4 g. A specimen with, apparently, a single range of dissepiments, and a central capillary axis 
projecting beyond the stipe. 
The forms given are quite variable, possessing a single character in common, that of 
continuous smooth margins. The specimens are all exceedingly compressed, and it appears 
as if the apparently continuous margin may be fallacious, or due to the expansion of the 
thin covering of the stipe beyond the edges of the serrse. This conclusion appears more 
reasonable when we compare the nearly direct and oblique dissepiments, corresponding to 
the G. bicornis and G. Sagittarius. The same character has been observed by Capt. Portlock 
(id cit ., pag. 321, pl. 20, figs. 2, 3 and 4). I cannot doubt but this one (represented in 
fig. 4 a, b ) is the form to which Hisinger applies the name of Prionotus scalaris. 
Position and locality. This species, fig. 4 c, occurs in the Utica slate, on West-Canada 
creek. The other specimens figured were all obtained from the Norman’s kill, near Albany. 
(State Collection.) 
