BIGSBY PALAEOZOIC ROCKS OF NEW YORK. 335 



whole of them have been obtained from the Lower as well as the 

 Upper Tertiaries ; and unless any dependence could be placed upon 

 the genus Astarte as somewhat characteristic of the Crag, there is 

 not another but has yielded several species throughout the whole 

 ot the Tertiary period. There are amongst these fossils several 

 impressions of what appear to have been the spines of a species of 

 Diadema ; and, although I have never met with this genus, Mr. Wood- 

 ward tells me he has seen a fragment of a spine from the Coralline 

 Crag, and it is au animal whose presence might be expected in that 

 formation. The shell (or rather the internal cast of it) which most 

 resembles an Eocene or Older Tertiary species is a Nucula with a 

 divergent hinge much like N. deltoidea, and this at first sight certainly 

 created considerable doubt as to its correct assignment; but our fossil 

 is considerably larger than any specimen or any figure belonging to 

 that species that I ha?e seen, though at the same time it is very 

 different from any Crag species. 



" Should these fossils be really the remains of a Crag period, I 

 think their resemblance is greater to the Older portion of the Upper 

 Tertiaries than to the Red Crag ; and as we have always been in the 

 habit of considering the Red Crag a deposit formed in a sea open to 

 the northward, with land on the south of it, the presence of the Co- 

 ralline Crag Formation thus elevated into land, whence these fossils 

 were procured, would not militate against such a supposition. 



" In the above list there are 4 species, viz. Dentalium costatum, 

 Nassa prismatica, Astarte Omalii, and Terebratula grandis, which, 

 although found in the Red Crag, did not, I think, belong to that 

 period, but were probably introduced into the deposit from de- 

 stroyed portions of the older bed. This would give to the Coralline 

 Crag a preponderance in number of what I have considered as iden- 

 tifications (or at least strong resemblances), making 14 for that for- 

 mation, and only 10 for the Red Crag." 



On the Palaeozoic Basin of the State o/New York. 



Part I. A Synoptical View of the Miner alogical and Fossil Cha- 

 racters of the Palceozoic Strata of the State of New York. By 

 J. J. Bigsby, M.D., F.G.S., Late British Secretary to the Cana- 

 dian Boundary Commission. 



[Read November 18th, 1857.] 



Introduction. — It having appeared to others as well as myself that a 

 resume, such as is contemplated by the above heading, is desirable, 

 I have attempted the task in the following pages. 



The characteristic geological points have been distributed under a 

 few heads, and then treated with brevity or fulness according to 

 the demands of the occasion ; — the heads being those of " mineral 

 character," "mode of transition " (among groups), "place," "posi- 

 tion or dip," "thickness," "fossils," in general (typical), "fossils 

 occurrent in Europe," " recurrent in New York." 



My hope and intention has been to form a standard of reference 



