328 FUCOIDES IN THE COAL FORMATIONS. 



whore I have spent much time in searching for fossil remains in these black shales, I have 

 seen them often covered with round spots of coaly matter, varying in diameter from half 

 an inch to one foot, showing no trace of organism, and resembling some kind of round, 

 hard Ulvacea?, like those which are seen in great quantity attached to the muddy shores 

 in shallow water. 



Descending further down in the Lower Devonian and Upper Silurian, we see there also 

 the rocks saturated with petroleum, and generally marked by an abundance of Fucoidal 

 remains. It is probably from the rocks of the Upper Silurian that Prof. Brogniart ob- 

 tained his Fucoides from Canada. In Ohio and other Western States, where the Upper 

 Silurian limestone is barren of remains, it does not show any deposits of petroleum. In 

 Canada the same rocks have both Fucoides and fluid bitumen. Prof. Lesley, after an ex- 

 amination of the east end of Canada, Gaspe, wrote me (5th January, 1866) : " All sorts 

 of marine vegetation of Upper Silurian and Devonian ages seem there in great abundance, 

 and petroleum everywhere in the Devonian, and oozing from the lower Helderberg lime- 

 stone formation." 



Still deeper the Lower Silurian has small deposits of bitumen in cavities of limestone, 

 even when every trace of organism has disappeared. This fact again is, I think, another 

 indication of the relation of petroleum to a marine vegetation. For it is well understood 

 that vegetable life has ruled the seas in its minute representatives, Diatomaceae, Desmi- 

 diaceae, long before animal life could be supplied or sustained by it. These diminutive and 

 primitive oil reservoirs are attributable to the concentration and decomposition of a local 

 surplus of that primordial vegetation. 



The geographical distribution of petroleum and that of the remains of marine Algae 

 present the same remarkable coincidence. At Oil Creek, Slippery Bock Creek, in the 

 Chemung of Virginia, Ohio, Kentucky, everywhere indeed where oil has been seen, either 

 in cavities or saturating the rocks, and where the strata were open to view, a remarkable 

 amount of Fucoidal remains has been observed. This cannot be a mere casual coincidence. 



The discussion presented in the last part of this paper may then be closed by this as- 

 sertion: That though the theory of the origin of petroleum from marine vegetables is not 

 yet supported by direct experiments and conclusive proofs, the reasons in favor of it are 

 weighty enough to merit due consideration. The more so, that if recognized true, the 

 theory presents an important chapter of the history of petroleum, and may prove of great 

 value in its application. 



