No. 487] PLEISTOCENE FLORA OF CANADA 449 



According to Rollick ('()(), 234) this species occurs in the Talbot 

 Formation of Maryland, and the leaflets figured by him are iden- 

 tical with those from the Don. 



Tilia americana L.— The exceedingly well characterized leaves 

 of the common linden or basswood, occur in the j^resent collection 

 in rather large numbers, some of them being fairly perfect. The 

 species is sparingly represented in the Don Pleistocene, since it 

 has been recognized in only one other collection. 



A recent note by E. W. Berry, ('07, 80) directs attention to the 

 occurrence of either T. americana or T. heierophylla in the Pleisto- 

 cene clays at Fisli House, New Jersey. The imperfect condition 

 of the fossils makes it impossible to determine their correlation 

 with one of the existing species, and in this emergency the specific 

 name T. diibium originally assigned by Newberry to the leaves, 

 is now retained but transferred from the genus Tilliaiphyllum, 

 and the citation therefore becomes Tilia diibia (Newb.) Berry. 



Ulmus americana L.— The common American or wdiite elm 

 has been identified on former occasions as a prominent constituent 

 of the Don flora, and it is once more represented in the present 

 collection from the same locality. 



Lesquereux ('83, pi. LIV, f. 10) has figured under the name of 

 U. pseudo-americana, a specimen from the John Day Basin of 

 Oregon (Upper Miocene) which very closely resembles the exist- 

 ing species and may well be regarded as its progenitor. 



In a report upon Tertiary plants from the region of the Interna- 

 tional Boundary in British Columbia, collected by Prof. R. A. Daly 

 in connection with the International Boundary Commission, and 

 now in course of publication, certain elms are described on the 

 basis of their wood structure, and it is seen that they differ but 

 little from some existing species. Among them there is one 

 which differs from the wood of the white elm to about the same 

 extent that the leaf of U. speciosa Newb. differs from its more 

 modern representative, U. americana. In a collection of woods 

 from the Pleistocene of Elmira, N. Y., now being studied, either 

 this or a closely related species is found, and the evidence there- 

 fore tends to show that Ulmus americana may be definitely traced 

 back into Miocene time. 



Ulmus pseudo-racemosa Hollick, has been found by Hollick 

 in the Sunderland Formation of Maryland ('06, 228), and this 



