4^8 PALiEONTOLOGY OP NEW-YORK. 



NOTE upon the Gcmis Gkaptolithus, and Descriptions of some remarkable new forms 

 from the shales of the Hudson-river group, discovered in the investigations of the 

 Geological Survey of Canada, under the direction of Sir W. E. Logan. By Jamks 



Hall. [ Communicated in April, 1855.] 



• 



The discovery of some remarkable forms of the Genus Graptolithus, during 

 the progress of the Canada Geological Survey, has given an opportunity 

 of extending our knowledge of these interesting fossil remains. Hitherto 

 our observations on the Graptolites have been directed to simple linear 

 stipes, or to ramose forms, which, except in branching, or rarely in having 

 foliate forms, differ little from the linear stipes. In a few species, as G. 

 tenuis (Hall) and one or two other American species, there is an indica- 

 tion of more complicated structure ; but up to the present time, this has 

 remained of doubtful significance. The question whether these animals, in 

 their living state, were free or attached, is one which has been discussed 

 without result ; and it would seem to be only in very recent times that 

 naturalists have abandoned altogether the opinion that these bodies belong 

 to the Cephalopoda. 



In the year 1847, I published a short paper on the Graptolites from 

 the rocks of the Hudson-river group in New- York : to the number there 

 given, two species have since been added from the shales of the Clinton 

 group. Other species, yet unpublished, have been obtained from the 

 Hudson-river group ; and since the period of my publication in 1847, large 

 accessions have been made to our knowledge of this family of fossils, and 

 to the number of species then known. The most important publications 

 upon this subject are Les Graptolites de Boheme, par J. Barrande, 1850; 

 Synopsis of the Classification of British Rocks, and Descriptions of Palaozoic 

 Fossils, by Rev. A. Sedgwick and Frederick M'Coy, 1851 ; Grauwacken 

 Formation in Sachsen, etc., von H. B. Geinitz, 1852. 



The radix-like appendages, known in some of our American as well as 

 in some European species, have been regarded as evidence that the animal 

 in its living state was fixed ; while M. J. Barrande, admitting the force 

 of these facts, asserts his belief that other species were free. It does not, 



