No. 186.] 47 



knowledge of the true forms and mode of growth of these fossils, 

 of which fragments and detached branches have for so many 3^ears 

 been described as complete forms. Neither up to that time, nor so 

 far as I am aware to the present, has any evidence of the existence 

 of perfect forms such as these been given to the public. 



Two of the species were described in the note transmitted to you 

 in 1855, and I have preceded the description of the remainder by 

 a rej^etition of that note. 



I have the honor to be, Sir, your most obedient servant, 



JAMES HALL. 



NOTE upon the Genus Graptolithus, and Descriptions of some remarJc- 

 ahle 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 James 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, diifer little from the 

 linear stipes. In a few species, as G. tenuis ( Hall ) and one or two 

 other American species, there is an indication 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 unpublislied, 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. Barhande, 1850; Synopsis of the 

 Classification of British Rocks, and Description of Palaeozoic Fossils, 

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

 Formation in Sachs en ^ etc., von H. B. Geinitz, 1852. 



