STUDY OF THE GRAPTOLITES. 205 



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

 on the '■'■ Zoological Affinites of GraptoUtes"* in which he has endeavored 

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

 as illustrated by MtJLLER. 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 larvae like- 

 wise bear a resemblance to the Graptolites figured by Mr. Suess ;t and 

 there are still farther analogies pointed out by Mr. M'Crady, 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 extension of true cellules, each one 

 having an independent aperture, and communicating with a common 

 canal, should oflFer 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 proportion of the species and genera appear never to have 

 been attached to the sea-bottona. 



It may not be easy to determine precisely the family to which these 

 graptohtic forms should be referred ; nor is it certain that the extensive 

 series now presented can all properly be referred to a single family. 

 Gen. Portlock has suggested that these bodies may constitute " several 

 genera belonging even to more than one order."J That they are true 

 Polypi, belonging to the Hydrozoa, I believe we shall be able to show, 

 both from analogies already established by various authors, and also 

 from their mode of development or reproduction as exhibited in some of 

 the species. 



The specimens which have usually been observed or represented are 

 simple disconnected stipes, doubtless the dismembered or fragmentary 



* "Remarks on the Zoological Affinities of the Graptolites, by John M'Crady, made before- 

 the Elliott Society of Natural History of Charleston, S. C, at the meeting of July 15, 1857." 

 [Extract from the Proceedings, vol. i.] 



t JVaturivissenchaflliche Abhandlvngen, Vierter Band, Tab. viii and ix. 



t Geological Report on Londonderry, &c., p. 318. 



