1865.] GRAPTOLITES OF THE QUEBEC GROUP. 43 



occurring in the Quebec group of Canada, and described in this 

 memoir, are fifty-three in number. 



The affinities of the graptolites have been a subject of much 

 discussion. Prof. Hall, after noticing the various opinions which 

 have been entertained, shows good reasons for the view that they 

 were Hydroids, approaching to the modern Sertularidce, a view 

 which General Portlock has also maintained. We quote some- 

 what at length the statements bearing on this point, referring our 

 readers to the work itself for the details of structure and syste" 

 matic descriptions. — Eds.] 



Until recently the 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 frag- 

 mentary, and, though varying somewhat in their proportions, 

 rarely exhibited anything that could be regarded as the commence- 

 ment or termination of their growth or development. These 

 bodies, in their flattened condition, present a range of serratures 

 either on one or on both sides of the stipe ; and seldom preserve 

 more of their substance than a carbonaceous or corneous film or 

 test of extreme tenuity. 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, witty 

 transverse indentations across the central portion of the stipe. This 

 appearance we now know to be due to the direction of the pres- 

 sure 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 vegetable origin ; and they have been thus considered by some 

 authors even at a very late period. Subsequently, they were 

 referred by Wahlenburg, and after him by Schlotheim, to the 

 Cephalopoda, being regarded as extremely slender orthoceratites. 

 This opinion may have received support from specimens in such 

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

 each side by a continuous margin ; but in such as present a single 

 or double series of marginal serratures, the analogy seems very 

 remote. Professors Geinitz and Quenstedt advocated the same 

 view at a much later date ; though it has since been abandoned by 

 these authors, from more extended investigations. 



