JEFFREY. — NATURE OF SOME SUPPOSED ALGAL COALS. 289 



spores, which in contrast to those occurring in cannels are predomi- 

 nantly of large size, and are as a consequence in all probability to be 

 regarded as macrospores. The tendency of water action, under which 

 it is universally agreed both cannels and bogheads were laid down, 

 would be to bring about a greater degree of concentration of the larger 

 and heavier bodies, the macrospores. 



At the present time the algal hypothesis is applied not only to the 

 origin of boghead coals, but is extended also to the question of the origin 

 of petroleum. If we assume that those bodies, which afford on distil- 

 lation the greatest amount of petroleum, are as it were the mother 

 substance of petroleum, the conclusion cannot be avoided that boghead 

 coals and similar substances are the source of petroleum-like com- 

 pounds. As has been pointed out above, we cannot with a due con- 

 sideration of the microscopic structure of boghead coals regard them 

 as composed of remains of Algae. The algal hypothesis of the origin 

 of petroleum consequently, so far as it rests on the structural compo- 

 nents of bogheads, falls to the ground. It is further invalidated by the 

 relatively small quantities of boghead coals found throughout the world. 

 The result of the present investigations is to show that bogheads are 

 essentially similar in their composition to the much more abundant 

 cannels. Consequently we are able to draw not only on the structure 

 of the relatively small amounts of boghead coals for a hypothesis as to 

 the origin of petroleum, but also upon the relatively abundant cannels, 

 which are widely distributed in the Northern Hemisphere, where 

 petroleum deposits are likewise abundant. The conclusion appears 

 obvious that the innumerable spores of Paleozoic Pteridophyta laid 

 down in enormous quantities on the bottoms of the shallow lakes or 

 lagoons, in which the Coal Period proper abounded, have furnished the 

 raw material from which in the course of countless years, as a result 

 of great pressure and perhaps of high temperature as well, the enor- 

 mously valuable petroleum products have been elaborated. 



The discussion of the possibility of the formation of algal peats under 

 modern conditions has not been entered upon in the present article 

 because that subject will be considered in a subsequent communication. 



Summary. 



1. The organisms found in abundance in boghead coals are not of 

 the nature of colonial gelatinous Algae, as has been asserted by 

 Renault, Bertrand and Potonie on the basis of the examination of a 

 small number of insufficiently thin sections of such coals. 



2. The bodies in question, as revealed in thin serial sections, made 



VOL. XLVI. — 19 



