1S76.] Knowledge of the Fossil Flora in India. 337 



film. It seems that Mr. Wood-Mason's plants are from a different clay- 

 band. 



In the description of the fossils I will always first discuss those 

 brought by Mr. Wood- Mason, which are mostly figured, briefly mentioning 

 the other plants known from the Raniganj field. 



1. EQTJISFTACEJS. 



Fossil Fqiiisetacece are known to occur throughout all the sedimentary 

 rocks from the Devonian unto the present time. But I think this 

 is so with the greatest portion of fossils, and has no consequence as 

 to the possibility or impossibility of determining the age of a certain group. 

 There are always certain differences which enable us to use a fossil organism, 

 although it has some or very close relation in the present world, as a guide 

 in determining the age. 



So it is with the Equisetacece too ; each of the formations has 

 its peculiar forms, some of which have more or less perfect representatives 

 in the living Equisetum, having a complete spathe in the artieula of the 

 stalk, while some others have no longer any existing analogues. 



As far as I can say the peculiar forms are just in those epochs, where- 

 in the Equisetacece are most richly developed, as in the palaeozoic and 

 mezozoic epoch (here esj)ecially in the Trias). 



The palaeozoic epoch is chiefly characterized by the following : — 



a. Catamites, Bgt. 



b. Aster opliyllites, Bgt. 



c. Macrostachia, Schimp. 



d. Cinyularia, Weiss. 



e. Splienopliyllum, Bgt.* 



The mezozoic is marked by the following peculiar genera : — 



a. Scliizoneura, Sissimp. 



b. Fhyllotheca, Bgt. 



c. Sphenopliyllum — a peculiar form. 



d. Vertebraria, etc. 



The genus Equisetum of the fossil Flora agrees, as I have already 

 said, with living forms ; and some forms which one takes as Catamites are 

 certainly casts, and perhaps sometimes stalks of other Equisetacece, as 

 well as the lower carboniferous genera Stigmatoeanna, Anarthrocanna, etc., 

 are nothing but forms of Catamites with scars disposed in regular arrange- 

 ment. 



* Sphenophyllum has long since ceased to be peculiar to the carboniferous epoch, as 

 we know it from Permian and also from the Triassic Damudas. 



