PLATE 72. 



Fig. 1. 321. 2. Graptolithus pristis. (Pag. 265.) 



i a. A fragment of arenaceous slate from the Hudson-river group at Turin, preserving the base of several 



specimens. I 6. A portion of the same magnified. 



I c. A magnified fragment of the same species on the opposite side of this specimen, showing obtuse serratures. 

 1 rf. A specimen of the same species from tlie black slate of Oxtungo creek, south of Fortplain, 

 1 ^. A magnified portion of the same. 



1 y. A fragment of the same species from the olive slate of the Hudson-river group at Loraine. 

 1 g. The same magnified, showing the obtuse termination of the teeth. 



1 A. A specimen from the olive slate in Lewis county. 1 i. A magnified portion of the same. 



1 ft. A narrow and somewhat more finely serrated specimen from the Utica slate. 1 /. The same magnified. 

 I m. A small specimen, showing the axis extending beyond the serrated portion in both directions. 

 1 n. The same magnified. 



1 o. A fragment of the same ffom the black slate of the Hudson-river group near Albany. 

 I p. A magnified portion of the same, showing the acute teeth near the base, and the broader obtuse ones above. 



1 r. This specimen resembles G.foliaceus of Murchison, and difiers slightly from the preceding in the short 



mucronate points of the teeth shown in the magnified portion I s : in other respects it is similar. 



Fig. 2. 322. 3. Graptolithus secalinus. (Pag- 267.) 



a a. A portion of the surface of a lamina of the Hoosick slate, with specimens of this fossil presenting some 

 variations in character. The broader one crossing the figure has the form and appearance of Prionottis 

 folium of HisiNGER ; but it is evidently only a more extenuated form of the same species as the more 

 elongated and narrower ones. 



2 It, b. Fragments of the slate from Baker's falls, with forms intermediate between the more expanded varieties 



of G. jwistis and those from Hoosick. 

 2 <•. A specimen from Hudson, where the slates arc partially metamorpliic, but much less thinly laminated, 

 and the fossils less expanded, than those at Baker's falls or at Hoosick. 



