F O X n I L L S A N D L O W K K M K D I C I N p: B O W 39 



the alternativc of rcferrinG; the hirj^e suite of spccimens of this leaf type either to 

 8 spccies or to 1 spccies. The lattcr choice was inevitable, owing to the intergrada- 

 tions bctween the numerous variants. Such a course naturally has lcd to a large 

 synonjTny for this species as wcll as others whose leaves were present in large 

 numbers. As a consequence, however, it follows that the spccics representcd by a 

 large nunibcr of specimens are usually more rcliably identificd, and long synon^-mies 

 of such species tend to add to their value for both stratigraphic and purely botanical 

 purposes. 



In cases where only a few specimens of a given leaf type were obtained in the 

 collections, the specific identifications are somcwhat less positive. In some cases, 

 for example, the lack of preservation of some integral portion of a leaf has pre- 

 vented comparison with some previously described species. Final disposition of 

 such species must of necessity await the possibiUty of obtaining larger suites of 

 more complete specimcns. 



The generic rcferenccs of many of the Medicine Bow species are open to serious 

 doubt. Unless whoUy rehablc evidence to the contrary has been obtained, no new 

 generic names have been substituted for those previously applied to the species. 

 I-n many cases herbarium studies have convinced me that the generic references are 

 unquestionably incorrect, yet my study of thousands of herbarium sheets of othcr 

 genera have failed to reveal comparable leaf types. Although older generic refer- 

 ences are thus retained for convenience and for lack of positive evidence for changes 

 at the present time, it should be understood that such references have little botani- 

 cal significance and few if any physical conclusions can be drawn from them. It is, 

 of course, possible that rnany of the Upper Cretaceous genera have failed to survive 

 in modern forests. It seems more likely, however, in view of the close similarity 

 of some of the leaves and seeds to modern forms, that a continued search among 

 modern plants will ultimately bring out the true botanic relationships. The few 

 remains of seeds obtained in the collections have thus far been stubbornly unidenti- 

 fiable, or at best determined only within a limit of 6 to a dozen generic possibilities. 

 Possibly future determinations of petrified wood and spores may open the way to 

 unsuspected relationships. 



In most of the generic references previously made by other writers, their 

 temperate zone experience has been clearly manifest. The Medicine Bow flora 

 contains a number of distinctly warm temperate and subtropical elements, and 

 most of the genera suggested as alternatives to present references are of low latitude 

 families. It is, therefore, becoming increasingly evident that a better acquaintance 

 with more southerly forests will be necessary to a proper taxonomic study of the 

 fossil species. During the winter of 1931, I spent 3 months in the West Indies 

 and South and Central America studying the modern forests with Dr. Ralph W. 

 Chaney of the University of California, under the auspices of the Carnegie Institu- 

 tion of Washington. I have planned to extend these studies northward into Mexico 

 and the Gulf states during the coming year. It is hoped that these experiences 

 will lead materially to a bctter understanding of both the taxonomy and the 

 ecologj' of the late Cretaceous floras of the Rockj' Mountain region. 



