DESCRIPTION OF" A. 



POSSIL ALGA FKOM THE CHEMUNG OF NEW YORK 



WITH REMARKS ON THE GENUS 



HALISERITES Sternherg 



BY DAVID WHITE 



Plates 3, 4 



Though scores of fossil bodies from the Devonic and Siluric 

 in both Europe and America have been described and published 

 as seaweeds, few of them are now generally regarded as' 

 vegetable, the greater number having proved to be of animal 

 or mechanical origin. Even among those survivors whose out- 

 lines and superficial aspect would seem at once to proclaim 

 their unity with this great class of lower cryptogams, a very 

 small number only are wholly free from the suspicion that they 

 should be relegated to the sponges or the graptolites, or 

 -accounted for as the burrows of some other organisms. The 

 admitted identity of the small remainder of Paleozoic thallo- 

 phytes is in most cases based on the internal organization of 

 such fragments as are sofossilized as to reveal their microscopic 

 structure, rather than on their form and external characters. 



The unsettled and somewhat chaotic status of the supposed 

 Paleozoic algae can not be due to any lack of seaweeds during 

 Devonic or Siluric time. Plant life of this class must have been 

 and undoubtedly was in great abundance. The apparent rarity 

 of unquestioned Paleozoic algae is due in the first place to the 

 absence of hard parts in most seaweeds and the consequent 

 failure, except in extremely rare instances^ of preservation of 

 any portion of the plant, specially of fragments showing the 

 essential primary diagnostic details relating to anatomy or re- 

 production. Another partial explanation lies in the remarkable 

 similarities in form and habit between many algae and certain 

 contemporaneous low animal types, specially among the sponges 



^ Chiefly in tlie coralline types. 



