50® 
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 Nereograpsus, 
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, biit simply the decent track of a slug over the surface 
of the slates. The Genus Rastrites of Barrande has not yet been reco¬ 
gnized among American Graptolitidea. These forms are by Geinitz united 
to his Genus Cladograpsus, 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- 
nema will form a geiius of the Family Graptolitidece. 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 Caiiadian 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. 
