Alet. 16 



Algae {Thallasophytes. Sea-weeds), Coal Flora, Report P, 

 1880, 1884. Being generally of soft cellular tissue, are seldom 

 preserved in the rocks; those thrown up now on the sandy sea- 

 shores in vast abundance rapidly disappear by decomposition 

 and evaporation. Where the shore is muddy the clay absorbs 

 and retains a portion of the oils into which they are partially 

 decomposed ; and this is one explanation of the great black 

 shale formations^ like VIII h Marcelliis^ & VIII e Oenesee 

 which contain large percentages of bituminous matter ; 

 although much of this contained hydro-carbon seems to be the 

 product of the decomposition of macrospores and microspores 

 (large and small plant-seeds). The vast abundance of the fos- 

 sil forms or casts of seaweeds in the Chemung and Catskill 

 ( VIII g^ IX) strata of north western Pennsylvania, serves to 

 apply the same explanation for the origin of petroleum. In 

 the Arctic seas seaweeds now grow to a vast size, rivalling 

 large tree trunks. In the midile of the Atlantic circular cur- 

 rents bring together such quantities of living seaweed that an 

 area several hundred miles in extent, called the Sargasso Sea^ 

 struck the Phoenician seamen with alTright, and impedes the 

 progress of modern sailing vessels. A world of animal life, 

 fish, etc., feed in it; and this helps to explain the abundance of 

 fossil fishes in the Devonian rocks. Schimper (Pal. Veg. vol. 

 1, p. 149) asserts that seven or eight thousand species of living 

 seaweeds have been described. They form floating prairies on 

 the surface of the North Pacific ocean between Japan and the 

 Kurile islands. The absence of fossil seaw^eeds in the coal 

 measures is as remarkable as their abundance in the underly- 

 ing Devonian strata. Probably the first true fossil seaweed of 

 the coal measures ever noticed was the Taonurus {caiiler piles) 

 marginatus^ found by Lesquereux in 1865 (described in Trans. 

 Amer. Philos. Soc, 1866) as dim cocktail markings on a dark 

 grey lime shale, in the Pottsville conglomerate formation No. 

 X//, on Slippery Rock creek in Lawrence county, Pa., which 

 become distinctly visible when the stone is covered with water. 

 (Described in report J, p. 96.) No doubt these plants were 

 the lineal descendants of the Caudagalli (cocktail) seaweeds 

 of the early and late Devonian strata (For. F//, VIIL) Sea- 

 weeds however must have existed in some abundance in the 

 coal age. Paleophycus {}l2ill-=FuGoides antiguics^ Schimper) 



