SIS 



PALEONTOLOGY OF NEW- YORK. 



I have recognized in the Clinton group of New- York a species cor- 

 responding to this generic description, the R. venosus ( Pal. New- York, 

 Vol. ii, pa. 40, pi. a 17, f. 2), which is there described as a Graptolithcs. 

 In the Report on the Geological Survey of Canada for 1857, I have de- 

 scribed two other species. An examination of some specimens of another 

 similar form from the Hudson-river shales near Albany ( New- York) has 

 convinced me that one of these is sufficiently distinct to form the type of 

 a new genus, for which I have proposed the name Reteooraptus, from 

 its reticulated structure, and from the absence of serratures or cellules 

 reaching to the axis. 



Reteo^raptns j^einitziaiius ( n. s.). 



Stipes small, sublinear ; sides essentially parallel. Enveloping crust of the 

 stipe finely veined, somewhat thickened : the skeleton reticulate with 

 three or more rows or series of subquadrangular reticulations, without 

 midrib or central axis : no defined cellules or serratures ; margins with 

 projecting mucronate or recurved spinules. 



The specimens are nearly all deprived of their outer 

 crust, leaving the skeleton alone. 



The accompanying figure is from a specimen, twice 

 enlarged. 



Geological position and locality. In the shales of the 

 Hudson-river group : Near Albany. 



I am by no means certain that this fossil, in its perfect condition, or in all its 

 stages of growth, consists of three rows of cells. The structure and mode of growth 

 in these forms indicates that the cells increase by lateral extension; and a single 

 fragment in the collection gives some evidence of four rows of reticulations, as in 

 other forms of the genus. It is not improbable, also, that in entire specimens we may 

 find evidence of a central axis; since the implied mode of growth, in its similarity 

 to that of the graptolites, indicates this structure. 



