582 



HISTORICAL GEOLOGY. 



LIFE. 



Plants. — Among Algae, or Seaweeds, the most remarkable is the Spi- 

 rophyton Caudagalli. Fig. 850 represents a fragment of the plant. The 

 broad blade of the seaweed grows spirally about the central axis, much 

 like that of the erect Alaska seaweed, Thalassophyllum clathrus. The Nema- 

 tophyton (Dawson), Fig. 851, is a tree-like Fucoid. The specimen was found 

 in the lower part of the Devonian of Gaspe, Canada, where the stems are 



850-852. 



Fig. 850, Spirophyton Caudagalli ; 851, Nematophyton Logani (x J) ; 852 a, b, c, fruit of Charse ? Figs, from 



Hall, Dawson, and Knowlton. 



sometimes three feet in diameter. The presence of Charce, water-plants of 

 simple cellular structure (inferior to Mosses, but Equiseta-like in habit, and 

 now common in marshy places), has been rendered probable by the discovery 

 (first made by F. B. Meek) of minute calcareous fossils resembling their 

 fruit (spore-cases) (Figs. 852 a, b, c,), in the Corniferous limestone of Ohio, 

 and in the cellular chert at the Falls of the Ohio, near Louisville. 



The hornstone, or chert, in the Corniferous limestone, as shown by 

 M. C. White, is full of microscopic plants from g^Vo ^^ two ^^ ^^ ^^*^^ 

 in diameter ; and with them occur sponge-spicules and teeth of Annelids. 

 Fig. 853 : a to e are Xanthidia, spore-cases of Desmids (page 437) ; /, g, 

 conferva-like filaments, made of a series of cells ; i, a Diatom. Besides 

 these there are siliceous spicules of sponges, Figs, j, Jc, I, m, n; and o, p 

 represent portions of jaws of Annelids. The mass of the hornstone was 

 probably made out of siliceous sponge-spicules and Diatoms. 



