Genus Gruptoliihus. 141 



duals, maybemonoprtomdeanov diprimi&ecm, or both; and weshall 

 see still farther objections to this division, as we progress, in the 

 utter impossibility of distinguishing these characteristics under 

 eertain circumstances. We do not yet perceive sufficient reason 

 to separate the branching forms from those supposed to be not 

 branched, for it is not always possible to decide which have or 

 have not been ramose, 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. 



Mr. Geinitz introduces among the Graptolitidcw the genus Ne- 

 reograpsas, to include Nereites, Myrianites, JVemertites, and Ne- 

 mapodia. Admitting tl.ese 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 

 JVemapodia is not a fossil body, nor the imprint of one, but sim- 

 ply the recent track of a slug over the surface of the slates. The 

 genus Raslritex of Barrande has not yet been recognized among 

 American Graptolitidew. These forms are by Geinitz united to 

 his genus Cladograpsus, the propriety of which we are unable to 

 decide. 



The genus Gladiolites (JRetialites of Barrande, 1850, Grapto- 

 phyllia of Hall, 1849) occurs among American forms of the Grap- 

 tolilidece, in a single species in the Clinton group of New York. 

 A form analagous, with the reticulated margins and straight mid- 

 rib, has been obtained from the shales of the Hudson River 

 group in Canada, suggesting an inquiry as to whether the separa- 

 tion 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 hictyo- 

 nerna will form a genus of the family GraptoUlidece. The same 

 collection has brought to light other specimens of a character so 

 unlike anything heretofore described, that another very distinct 

 genus will thereby be added to this family. The Canadian speci- 

 mens show that the Graptoiites are far from always being simple 

 or merely branching flattened stems. 



The following diagnosis will express more accurately the cha- 

 racter of the genus Graplolithus, as ascertained from an examina- 

 tion of perfect specimens in this collection. 



