328 A. Rollick — Kenai Flora of Alaska. 



States or Canada with which it may be satisfactorily correlated. 

 It contains many species which are identical with those of cer- 

 tain well-defined Teitiary horizons in the United States and, 

 if these species were the only ones represented, the Tertiary 

 age of the beds in which they occur would not be questioned : 

 such species, for example, as Taxodium distichum miocenum 

 Heer, Pqpuhcs arctica Heer, P. Richardsoni Heer, Corylus 

 McQuarrii (Forbes) Heer, Carpinus grandis Ung., Betula 

 Brongniartii Heer, Paliurus Colombi Heer, etc. 



Associated with these, however, not only in collections from 

 a single locality but frequently in the same pieces of matrix, 

 are species which elsewhere occur in strata of recognized Cre- 

 taceous age, such as Adiantum formosum Heer, Sequoia rig- 

 ida Heer, Sagenopteris elliptica Font., etc., and others which, 

 if found by themselves, would almost certainly be considered 

 as closely allied to certain Jurassic species, such as Pterophyl- 

 lum concinnum, Heer, Anomozamites Schmidtii Heer, JVils- 

 sonia co?>itula Heer, etc.! 



When first examined,, it was thought that this association 

 of undoubted Tertiary angiosperm species with apparently 

 Mesozoic types of gymnosperms was impossible, and that col- 

 lections from different geologic horizons must have somehow 

 become mixed ; but the fact'that some of these diverse floral 

 elements were often included in the same piece of matrix 

 proved that they must have been synchronous. 



Discussion of the Flora. 



Unless all of our previous knowledge and experience in rela- 

 tion to the beginning and subsequent evolution of the angio- 

 sperms is at fault, it is evident that the presence of highly 

 developed angiosperm species in any flora at once precludes 

 the possibility of regarding it as Jurassic in age. Furthermore, 

 the fact that certain of the angiosperms in the flora under con- 

 sideration are undoubted Tertiary species makes it imperative 

 to regard the apparent identity of certain of the associated 

 cycads with Jurassic species as untenable and to regard such 

 apparent identity as due to superficial resemblances only. The 

 theory that a specific type could persist throughout such a 

 great length of time as that implied could hardly be accepted 

 on evidence based entirely upon such inconclusive factors. 

 The genera in which the species belong, however, are unques- 

 tionably identical with Jurassic generic types ; but it is more 

 logical to assume that such types could have continued into 

 Tertiary times than to imagine that highly developed angio- 

 sperms could have been in existence in the Jurassic period. 



While searching through paleobotanical literature for any 

 possible description of, or reference to, a flora similar to ours, 



