STUDY OF THE GRAPTOLITES. 171 



original to have been a Diplograptus, partly perhaps from a name applied 

 by LiNN^us, and also from the fact that we meet with numerous specimens 

 in this group presenting scalariform figures, as I have had occasion to show, 

 while they occur more rarely and less distinctly among the others. It is 

 scarcely probable that the figure of Ltnn^us was intended to represent a 

 fossil with rectangular cellules, like Climacograptus, notwithstanding the 

 figure of Prionotus scalaris of Hisinger is of that type ; nor does it seem 

 to me at all certain that the latter is identical with the species of 

 LiNNJEUS.* This question, however, is of minor consequence, since there 

 is no longer any important diflTerence of opinion among naturalists as to 

 the general nature and character of the fossil referred to in this descrip- 

 tion and figure of Graptolitkus. 



Until within a few years tho graptolites were, with two or three exceptions, 

 known only as simple, straight, or slightly curving linear stipes or stems, 

 usually lying in the same plane upon the slaty laminae in which they were 

 imbedded. Nearly all these were evidently fragmentary, and, though varying 

 somewhat in their proportions, rarely exhibited anything that could be 

 regarded as the commencement or termination of their growth or develop- 

 ment. These bodies originally consited of slender tubes, composed of a 

 corneous or chitinous substance, and having more or less gibbosity; but 

 in their flattened condition, seldom preserve more than a film of carbona- 

 ceous matter of extreme tenuity between the layers of fissile slate in which 

 they usually occur. The slender stipes present a range of serratures 

 either on one or on both sides. Under more favorable circumstances, 

 these serratures are discovered to indicate the apertures of cellules, 

 symmetrically arranged in reference to each other, and to the axis of the 

 linear stipe. Others show parallel entire margins, with transverse inden- 

 tations across the central portion of the stipe. This appearance we now 

 know to be due to the direction of the pressure upon the body exerted 

 at right angles to the cellules, and which will be explained in the sequel. 



The earliest opinion regarding these fossils was that they were of vege- 

 table origin ; t and they have been thus considered by some authors even at 

 a very late period. Brongniart, in his great work, Histoire des 

 Vegetaux Fossilea, has figured two species among the Algae. This reference 

 was followed in the earlier part of the Geological Survey of New- York by 

 Conrad, Mather, Vanuxem and Emmons. The animal nature of the 

 Graptolite was first recognized by Waloh, who figured two species which 

 he describes as small, toothed Orthoceratites. His view was subsequently 

 maintained by Wahlenberq, and after him by Sohlotheim, who referred 

 them to the Cephalopoda, regarding them as extremely slender Orthoce- 

 ratites. This opinion may have received support from specimens in such 

 condition as G. scalaris, where the indentations are limited on each side 



* I have olsowhore endeavored to show that G. scalaris is a diprionidian form, exhibit- 

 ing only one margin. « 



t BaoMEL (Acta Upsala, p. 312, 1727) referred the* Graptolites of Sweden to tho fossil 

 leaves of Grasses. 



