[PENHALLOw] THE PLEISTOCENE FLORA OF CANADA 61 



positions ol'rcsin-passages. Eadial sections show occasional rcsin-passages 

 containing nnnierous round masses of resin, occasional badly disorganized 

 bordered pits and numerous rather high medullary rays with lesinous 

 matter, and rather straight, thick-walled cells. 



The tangential sections show numerous rather high, uni-seriate rays 

 with thick-walled cells. Masses of resin are common. 



These two specimens cleai'ly represent the same kind of wood, and 

 it is at once obvious, from the details given, that there are very few and. 

 unsatisfactory details upon which to base a differentiation. Neverthe- 

 less, the character of the rays at once points to the fact that the w*ood is 

 either Larix or Flcea, an indication greatly strengthened by the occur- 

 rence of resin-passages, from which the presence of fusiform raj's may be 

 inferred, although these structures are not obvious, owing to the etfects 

 of decay and compression. Nothing beyond this can be determined con- 

 clusively, but on geographical grounds we would be led to the inference 

 that this species must be either L. americana or P. nigra. From this 

 point of view, then, the somewhat highly resinous ray-cells would lead 

 to the conclusion that the wood must be that of Larix americana, since 

 in Picea nigra the rays are but slightly resinous, and the walls of the 

 cells are much thinner. 



Our present knowledge of the Pleistocene tlora shows that this 

 species was a somewhat prominent element, and had a wide distribution 

 during that period, since it has also been found at Fort Madison, Iowa, 

 and in New Brunswick. The distribution thus indicated conforms to the 

 geographical range as we know it in existing representatives of this 

 species. 



Picea nigra. 



The specimen designated 44a evidently represented a small branch 

 which had become much flattened under pressure, in consequence of 

 which the structure, as displayed in transverse section, was much dis- 

 torted. Decay had also operated largely, so that only here and there was 

 the structure found to be sulficiently presei^ved to permit of a recognition 

 of details. From these it was possible to determine the following : 

 Transverse. Summer wood obscure. Spring tracheids large, thin-walled, 

 squarish, but chiefly much distorted. Eesin-passages rather abun- 

 dant and sometimes perfectly jjreserved, without thyloses, but with 

 thick-walled epithelium-cells, usually much distorted. Kays some- 

 what resinous. 

 Radial. Rays straight, thin-walled. 



Tangential. Ordinary rays with thick-walled, oval or oblong cells. Fusi- 

 form rays with large resin-passages without thyloses, but with thick- 

 walled epithelium. 



