I3O THE DAWN OF LIFE 



no mineralogist has yet succeeded in giving a feasible inor- 

 ganic explanation of the combination of canals, laminae, tubu- 

 lation and varied mineral character existing in Eozoon. 

 But then comes the strange fact of its apparent isolation with- 

 out companions in highly crystalline rocks, and with appa- 

 rently no immediate successors. This has staggered many, 

 and it certainly, if taken thus baldly, seems in some degree 

 improbable. Recent discoveries, however, are removing this 

 reproach from Eozoon. The Laurentian rocks have yielded 

 other varieties, or perhaps species of the genus, those which I 

 have described as variety Acervulina, and variety Minor, and 

 still another form, more like a Stromatopora, which I have 

 provisionally named E. latior^ from the breadth and uniformity 

 of its plates. 1 There are also in the Laurentian limestone 

 cylindrical bodies apparently originally tubular, and with the 

 sides showing radiating markings in the manner of corals, or 

 of the curious Cambrian Archaeocyathus. Matthew, a most 

 careful observer, has found in the Laurentian limestone of 

 New Brunswick certain laminated bodies of cylindrical form, 

 constituting great reefs in the limestone, and in the slates 

 linear flat objects resembling Algae or Graptolites, and spicular 

 structures resembling those of sponges. 2 Britton has also de- 

 scribed from the Laurentian limestone of New Jersey certain 

 ribbon-like objects of graphite which he regards as vegetable, 

 and names Archczophyton Newberryii? Should these objects 

 prove to be organic, Eozoon will no longer be alone. Besides 

 this the peculiar bodies named Cryptozoum by Hall, and which 

 are intermediate in structure between Eozoon and Loftusia, 

 have now been found as low as the Lower Cambrian. 4 Barrois 



1 Notes on Specimens of Eozoon, " Memoirs of Peter Red path Museum," 

 1888. 



2 Bui. Nat. Hist. New Brunswick, No. IX., 1890. 



3 Annals N. Y. Academy of Science, 1888. 



4 Walcott, Lower Cambrian, 1892. 



