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Cincinnati Society of Natural History. 



and found that many of the fossils previously referred to the Algae were 

 inorganic in their origin, and that many more were casts and impressions 

 of trails and burrows. It is but fair to state, however, that Saporta, of 

 France, does not agree with Nathorst. The observations in the present 

 paper accord with those of the Swedish naturalist. 



After speaking of the character of certain other fossil marks, and refer- 

 ring them to the tracks of worms of different sorts, Nathorst says of the 

 species of the Contributions to Palaeontology, of Miller and Dyer: 



"In the same way all the Algaj of the Cincinnati group,' described by 

 Miller in 1874, and with Dyer in 1878, must be either traces of animals 

 or objects of purely mechanical origin. Thus, the Bnfhotrephis r'imuh^ii> 

 (Miller, 1874) is of the same species as the greater part of the Chondrites ; 

 the Blastophycus and the Trichophycus are of purely inorganic origin 

 (drops or courses of water?); the Rusophycus asper is a track similar to 

 that of the Synapta or of the Nychvt, while the Licrophycus JlabeUum 

 must be the track of a worm, or, perhaps, of an Ophiuridian. The Dac- 

 tylophycus is, perhaps, the molding of worm-holes: t he Heliophyciu might 

 be the impression of a medusa; the Dystactophycus is undoubtedly of 

 inorganic origin; the ChloephycuSj of which I saw a specimen in Sweden, 

 is most assuredly a result of running water (all the stems are turned to 

 the same side); and, finally, the Arisiophycus can hardly be anything but 

 ridges on the surface of the rock. No one of them has any resemblance 

 to the Algae ; but the American paleontologists, as shown above, have 

 long had the habit of describing all doubtful objects as belonging to this 

 vegetable group, whatever may be otherwise their aspect and their struc- 

 ture." 



The above quotation is given as corroborative evidence of the position 

 taken in the present paper. It is desired to have it distinctly understood 

 that my own ideas and theories were developed entirely independently of 

 those of Nathorst, whose memoir I never saw until this paper was nearly 

 ready for publication. 



