172 TWENTIETH EEPORT ON THE STATE CABINET. 



by a continuous margin ; but in sucb 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, Bceck supposes the graptolites may have been the arms 

 of Radiata or Cephalopoda. 



Prof. NiLSSON first suggested the true relations of these fossils, and 

 maintained that graptolites were Polyparia, belonging to the Family 

 Ceratophyta. Dr. Beck, of Copenhagen, regarded them as belonging to 

 the Group Pennatulidae, of which the Linnean Virgularia is the most 

 nearly allied existing form. Sir Roderick Murchison has adopted this 

 view of the relations of the graptolites in his Silurian System. * General 

 PoRTLOCK has fully recognized the graptolites as zoophytes, and has pointed 

 out their analogy with Sertularia and Plumularia. 



The relations of graptolites with the Cephalopoda had already been fully 

 disproved by M. Barrande (in the first chapter of his ''^Graptolites de 

 Boheme^^)y before the abundant materials for the refutation were discovered 

 in the remarkable forms of the Quebec group ; and most naturalists were 

 already agreed in referring these bodies to the Class Polypi, to which they 

 doubtless belong. 



More recently, Mr. M'Cradt, of South-Carolina, has published a paper 

 on the "Zoological Afiinities of Graptolites,"! in which he has endeavored 

 to show the similarity of the graptolitic forms with the echinoderm larvae 

 as illustrated by Muller. There is certainly much resemblance between 

 the enlarged figures given by that author, and some forms of graptolites in the 

 shales of the Hudson River valley; while some of the figures with central 

 discs have a more remote analogy with certain forms from the Quebec 

 group. Some of the toothed rods of the echinoderm larva9 likewise bear 

 a resemblance to the graptolites figured by Mr. SuESS ;1 and there are still 

 farther analogies pointed out by Mr. M'Cradt, which, however, may not 

 be regarded as of equal value by the greater number of naturalists. 



For my own part, although admitting the similarity of form and of some 

 of the characteristics which were very kindly pointed out to me by Mr. 

 M'Crady, long before his publication, I cannot recognize the analogy 

 sought to be demonstrated. The establishment of the fact that these 

 toothlets or serratures are the extensions of true cellules, each one having 

 an independent aperture, and communicating with a common canal, should 

 offer convincing argument against these bodies being other than polyp- 

 bearing skeletons. But, in following the extensive series of forms now 

 presented to us, we have much evidence to show that some of these were 

 attached to the bed of the ocean, or to other bodies ; while the greater 



•Silurian Syatem, page 694; and letter of Dr. Beck, pp. 695-6. 



f "Remarks on the Zoological Affinities of the Graptolites, by John M*Crady, made 

 before the Elliot Society of Natural History of Charleston, 8. C, at the meeting of July 

 15, 1857." [Extract from the Proceedings, vol. i.] 



t Naturwissenschaftliche Abhandlungen, Vierter Band, Tab. viii and ix. 



