426 



MEMOIRS OF THE NEW YORK BOTAKICAL GARDEN 



concerned. Unfortunately, however, our knowledge of the Plio- 

 cene flora, esfjecially the American Pliocene, is exceedingly lim- 

 ited,** and hence we have a very unsatisfactory concept of the 

 North American flora that was intermediate between that of the 

 Miocene and that of the Pleistocene. We also know relatively 

 little of the American Pleistocene floras, compared with the ex- 

 tensive knowledge that has been acquired of the floras of the 

 same period in Europe; hence satisfactory paleobotanical data 

 for correlation jDurposes are meager and inconclusive. 



Dawson, Penhallow, and other Canadian geologists*''^ recog- 

 nized three distinct Pleistocene climatic periods, viz. : 



3. Green's Creek: Mild. About the equivalent of that of the 

 northern United States at the present time. 



2. Scarboro : Cold. About the equivalent of that of Labrador 

 at the present time. 



1. Don: Warm temperate. About the equivalent of that of 

 the middle eastern United States at the present time. 



Of the seventy-five species of fossil plants listed in these re- 

 ports {loc. cit.) all are living, with one exception {Acer pleisto- 

 cenicum Penh.), and all have a wide geographic and climatic 

 range, with one exception {Qtiercus ohlongifolia Torr., confined 

 to California). The species of greatest southern range, which 

 may be regarded as indicating warm-temperature conditions in 

 connection with the Don flora are : 



Chamaecyporis sphneroidea Spach [=C. thyoides (L.) B. 

 S. P.]. Mississippi to Massachusetts. 



J'uniperus virginiana L. West Indies and Arizona to New 

 BrunsAvick. 



Quercus ohtusiloba Michx. [=Q. minor (Marsh.) Sarg.] 

 Texas to Missouri, and cultivated in the northern states. 



48 Only two papers of any importance have been published, viz.: (a) A Pliocene 

 flora from the coast ranges of California. Harold Hannibal. Torrey Bot. Club, Bull, 

 vol. 38, pp. 329-342. July, 1911. (b) The flora of the Citronell formation. E. W. 

 Berry. [In] Matson, G. C, and Berry, E. W. The Pliocene Citronelle formation of 

 the Gulf coastal plain and its flora. U. S. Geol. Survey, Prof. Paper 98-L, pp. 193- 

 208, pis. 44-47. 1916. 



49 Dawson, J. W., Penhallow, D. P., and others, (a) Canadian Pleistocene flora 

 and fauna : Eeport of the committee . . . appointed to further investigate the flora 

 and fauna of the Pleistocene beds in Canada. British Assoc. Adv. Sci., Eept., Bristol 

 meeting, 1898, pp. 522-529. (b) Idem, Sec. C, Bradford meeting, 1900, pp. 328-339. 



