0. Holtedahl — Permian of England. 



195 



Aet. XIII. — On the Occurrence of Structures like Wal- 

 cott's Algonkian Algce in the Permian of England; by 

 Olaf Holtedahl. 



During liis studies on the Paleozoic rocks of Finmarken 

 and Bear Island, the writer became acquainted with the 

 peculiar organism-like structures in dolomites and lime- 

 stone which American paleontologists have generally 

 referred to Cryptozoon. In a summary of my strati- 

 graphical results in Finmarken published in this 

 Journal in 1919/ the opinion was stated that the Crypto- 

 zoon ''species," such as Gymnosolen ramsayi described 



^^^ 



^h 



^^s 



#^ 



r^^'i-' 











Fig. 1, — Four-fifths nat. size, 

 eott. 



Compare with N eivlandia frondosa Wal- 



by Steimnann from northern Russia, can not be regarded 

 as real fossils which deserve generic and specific names, 

 but rather that this type of sedimentary rock must be 

 considered to represent ''a chemical precipitation, one, 

 however, that probably came into existence through the 

 organic processes of living organisms." Accordingly, 

 as a general term for these structures, which appear to 

 be genetically related to oolites, it was proposed that we 

 should use Kalkowsky's name stromatolites. 



As to the kind of organisms which may have played a 

 part in the process by which the stromatolite laminae were 

 precipitated, I mentioned, among others, the cells of blue- 

 green algae described by Walcott from Camasia spongiosa 



^ Vol. 47, p. 96. 



