90 PALiBONTOLOGY OF NEW-YOKK. 



in the Palaonlology of Russia and the Ural Mountains, as cited above, which are the only 

 authorities within my reach. 



The specimens examined are very imperfect, consisting first of a column and a few 

 scattered plates, which were collected by myself in 1835 ; and subsequently, since the first 

 pages of this report had passed through the press, of some more perfect specimens, collected 

 by Dr. Budd, in Lewis county, who has kindly forwarded them for my examination. 



There are some slight differences observable between the European species and this one, 

 the most obvious of which is the greater elongation and breadth of the cup near the top in 

 the latter. This feature, however, may be due to compression ; as the condition of our 

 specimens, which are imbedded in a shaly calcareous mass and usually crushed, does not 

 admit of minute comparison. 



The occurrence of this fossil, so nearly allied to, if not identical with, the Russian species, 

 is an exceedingly interesting circumstance, since all the specimens before known are from 

 a single locality (Pulcowa) in Russia. The position also corresponds precisely ; for, in that 

 country, these peculiar fossils occur only in the lower part of the Silurian system. So true 

 is it that certain organic forms are reliable in the determination of the age of certain 

 formations,, that M. de Verneuil, on seeing my specimens, pronounced the rock, without 

 hesitation, the Trenton limestone, which rock is unquestionably identical with the great 

 Orthoceratite limestone of Russia and Sweden. 



The illustrations which I have been able to give, are the following : 



Fig. 4 a. The column, with a single detached plate near its uppei termination. The long narrow joints 

 of the column, which gradually become shorter and broader until they form broad thin rings 

 in the upper part, are clearly shown. The plate belongs to the second range, and is hexagonal, 

 with three prominent ridges upon its surface. A curved depression on one side shows that it 

 formed a part of the lateral aperture. 



Fig. 4 b. Part of a similar column, with the plates of a crushed cup lying at its upper termination. 

 There are, at the summit of this specimen, one or two free nearly circular discs, and one 

 apparently attached, as if forming the base of the tentacula at one point. 



Fig. 4 e. One of these plates enlarged. The surface is worn smooth, with the exception of the ridges 

 upon the plate, but this is doubtless due to maceration and abrasion. 



Fig, 4 i. A larger and more perfect specimen ; the plates near the base showing the strong strise upon 

 their surface, which are at right angles to the edges. 



Fig. 4 t. The structure, as far as can be ascertained from our specimens. 



Fig. 4 /. The surface of one of the plates, magnified, to show the striae. 



Position and locality. The specimens first obtained are fVom the midst of the fossiliferous 

 portions of the Trenton limestone, associated with C/uetetes, Orthis testudinaria, ifc. The 

 last are from a stratum upon which a layer of shaly matter has been deposited, imbedding 

 the fossils. The rock contains no other fossils. Turin, Lewis county. 



