[PENHALI.OW] NOTES ON TERTIARY PLANTS 47 



expedient to designate it for the present by a separate name for which 

 C. dawsoni seems appropriate. The diagnosis is as follows: — 



Transverse. — Growth rings rather broad. Tracheids of the spring wood large, 

 thin-walled and squarish, the structure passing gradually into the 

 thin summer wood composed of 2 — 4 rows of radially flattened 

 thicker-walled tracheids. Medullary rays very resinous. Resin cells 

 numerous throughout the growth ring, and chiefly disposed in 

 tangential rows. 



Radial. — Medullary rays very resinous, devoid of tracheids; the lateral walls 

 with oval or round pits, several per tracheid; the upper and lower 

 walls entire; the terminal walls entire, straight or curved. Wood 

 tracheids with large bordered pits in one or sometimes two rows. 



Tangential. — Medullary rays very resinous, strictly uniseriate; the cells large, 

 thin-walled and transversely oval or oblong. 



PsEUDOTSUGA MiocENA, Penh. 



Figs. 12-13. 



Miocene of Cariboo, B.C. 



Eocene of the Great Valley and Porcupine Creek Groups, N.W.T. 



Bib. :— Trans. R. Soc. Can., VIII., iv., 68, 1902; Brit. N. A. Bound. Comm., 1875. 

 93-97; App. A, 331; Knowlton Cat. Cret. and Tert. Floras, 80, 227. 



This species was first recorded from the Cariboo mine at Cariboo, 

 B.C., in 1903,^ the description being based upon a specimen of poorly 

 preserved wood. So far as I am aware, this formed the first recognition 

 of the genus in a fo'ssil state in America. The plant once more ap- 

 pears in an earlier horizon, this time in the Eocene deposits of the 

 Great Valley Group, N.W.T., near the forty-ninth parallel. There 

 is no previous record of this wood from that locality, and in an examin- 

 ation of this same material in 1875,- Sir William Dawson failed to 

 identify it. On examining his descriptions, however, I find a number 

 of coniferous woods which he assigned to the genus Cupressoxydon 

 and distinguished by letters only. He further pointed out that the 

 woods thus provisionally included, might in reality represent several 

 genera. Among these species (/) is probably identical with the one 

 now under consideration. 



I also find reference to a Taxoxylon which is not specifically 

 described,^ but said to be distinguished by "spirally lined wood cells 

 of the type of those in the modern Taxus, and discs with a slit instead 

 of a round pore." No taxine wood is to be found in the collection, 



"■ Trans. R. Soc. Can., VIII., iv., 68, 1902. 

 * B. N. A. Bound. Comm., 1875, App. A, 331. 

 =* B. N. A. Bound. Comm., 1875, App. A, 331. 



