SOO PALAEONTOLOGY OF NEW-YORK. 



for it is not always possible to decide which have or have not been ra- 

 mose, among the fragments found. Moreover there are such various modes 

 of branching, that such forms as G. ramosus present but little analogy 

 with such as G. gracilis. 



M. Geinitz introduces among the Graptolitidea the Genus Nereograpscs, 

 to include Nereites, Myrianites, Nemertites and Nemapodia. Admitting the 

 first three of these to be organic remains, which the writer has elsewhere 

 expressed his reasons for doubting, they are not related in structure, 

 substance, or mode of occurrence, to the Graptolites, at least so far as 

 regards American species ; and the Nemapodia is not a fossil body, nor 

 the imprint of one, but simply the recent track of a slug over the surface 

 of the slates. The Genus Rastrites of Barrande has not yet been reco- 

 gnized among American Graptolitidca,. These forms arc by Geinitz united 

 to his Genus Cladogkapsus, the propriety of which we are unable to decide. 



The Genus Gladiolites ( Retiolites of Barrande, 1850 ; Graptophyllia 

 of Hall, 1849) occurs among American forms of the Graptolitidea in a 

 single species in the Clinton group of New- York. A form analogous, with 

 the reticulated margins and straight midrib, has been obtained from the 

 shales of the Hudson-river group in Canada ; suggesting an inquiry as to 

 whether the separation of this genus, on account of the reticulated 

 structure alone, can be sustained. In the mean time we may add that "the 

 Canada collection sustains the opinion already expressed, that the Dictyo- 

 H£MA will form a genus of the Family Graptolitidea. The same collection 

 has brought to light other specimens so unlike anything heretofore de- 

 scribed, that another very distinct genus will thereby be added to this 

 family. The Canadian specimens show that the Graptolites are far from 

 always being simple or merely branching flattened stems. 



The following diagnosis will express more accurately the character of 

 the Genus Graptolithus, as ascertained from an examination of perfect 

 specimens in this collection. 



