wAiiD.] DISCUSSION OF THE TABLE. 535 



Carpolithes horridus. To the parts represented there our specimens add 

 the complete rays showing what is probably the spore-bearing portion 

 at their extremities. 



Other Cretaceous forms might be mentioned, but the above-named 

 types are sufficient to show that the flora of the Laramie group certainly 

 possesses a strong Cretaceous facies, and in very many respects agrees 

 with that of the Seuonian or highest member of that formation where- 

 ever this is known to contain vegetable remains. I do Dot wish to be 

 understood as arguing that the Laramie is a Cretaceous deposit, but 

 rather against the view maintained by Mr. Lesquereux that it is neces- 

 sarily Eocene. I am still free to admit that, so far at least as the Fort 

 t'nion group is concerned, the flora is closely in accord with that of the 

 European Miocene, in which nearly all its genera and many of its spe- 

 cies are represented ; and but for the occurrence of these anomalous, 

 archaic forms, which become more and more frequent as the material 

 for study increases, it would be impossible to deny that the flora at 

 hast was Miocene. In this, however, one fallacy should be avoided, 

 which is, I think, the one that so strongly biased Professor Heer in 

 favor of referring new and imperfectly known floras to the Miocene. 

 The immense number of fossil plants that are known from that forma- 

 tion—over 3,0(10 species — greatly increases the chances of finding the 

 analogue of any new form among its representatives. While, for ex- 

 ample, there are probably many more Laramie forms that have nearer 

 allies in the Miocene flora than in that of any other age, still, relatively 

 to the number of Miocene species, the Eocene or Senonian types would 

 outweigh them. But the same canon must be applied in comparing the 

 Laramie with these latter. If the relationships were about equal we 

 should require a larger absolute number of Eocene forms, because the 

 Eocene flora is larger 



Taking all these facts into consideration, therefore, I do not hesitate 

 to say that the Laramie flora as closely resembles the Senonian flora as 

 it does either the Eocene or the Miocene flora. But again, I would in- 

 sist that this does not necessarily prove either the Cretaceous age of the 

 Laramie group or its simultaneous deposit with any of the upper Cre- 

 taceous beds. The laws of variation and geographical distribution for- 

 bid us to make any such sweeping deductions. With regard to the 

 first point it is wholly immaterial whether we call the Laramie Cre- 

 taceous or Tertiary, so long as we correctly understand its relations to 

 the beds below and above it. We know that the strata immediately 

 beneath are recognized upper Cretaceous and we equally know that 

 the strata above are recognized lower Tertiary. Whether this great 

 intermediate deposit be known as Cretaceous or Tertiary is therefore 

 merely a question of a name, and its decision one way or another can- 

 not advance our knowledge in the least. 



With regard to the synchronism, as already remarked, it would cer- 

 tainly be interesting and important if we could know with certainty 



