UTICA SLATE AND HUDSON=RIVER GROUP. 265 
GRAPTOLITES OF THE UTICA SLATE AND HUDSON-RIVER GROUP. 
The fossils of this genus are numerous in many localities of the Utica slate, as well as 
in the succeeding greenish or olive shales. In the same shales and slates along the Hudson 
river, they are more numerous, both as individuals and species, than in any other part of 
the State, or perhaps of the Continent. This genus, which recently contained but a few 
species, has become so augmented that it now numbers not less than twenty distinct 
forms. In consequence of these fossils being usually imbedded in shale, and often 
extremely compressed, some doubt of their true nature has been entertained, and by 
some authors they have been placed among plants. When imbedded in calcareous matter, 
they often preserve their original form and proportions, and reveal more clearly their 
true character. In this condition, they show a more close analogy with the Linnean 
Vireutaria than with any other among living forms.’ This opinion has already been 
advanced by Dr. Beck of Copenhagen ( Murcutson, Sil. System, p. 695); and an inspec- 
tion of the figures of G. bicornis, from specimens in limestone ( Plate LX XIII, figs. 2 
m and m'), will sustain this view. Judging from this and several other well preserved 
specimens, all the GraproLitEes possessed a semicalcareous body with a corticiform 
covering ; which latter, entirely compressed, is all that is usually preserved in the slates. 
32]. 2. GRAPTOLITHUS PRISTIS. 
Pu. LXXI. Figs. 1 a-s. 
A 
Prionotus pristis. Histncrer, Leth. Suecica, 1837, pag. 114, pl. 35, sup. fig. 
Compare Graptolithus foliaceus, Murcuison,” Sil, System, 1839, pl. 26, fig. 
we 
‘Linear, straight, scarcely a line broad, compressed ; rachis central, capillary ; both sides 
with broad acute teeth.” 
This description of H1sineer corresponds precisely with the most abundant and widely 
distributed species of this genus which we have in the older slates. The species occurs in 
small short fragments, and in forms which appear to be nearly entire, having a length of 
two inches. When the specimens are flattened, a central capillary axis is very perceptible, 
extending the entire length. In some specimens where the serrated portion is removed, 
* PorTLocx is inadvertently cited as authority for this species, on page 79 of this volume. 
| Pat#zonrToxoey. } 34 
