XLVn] SEQXTOIINEAE 347 



genial south on the American continent than in Europe where the 

 retreat from Arctic regions ended in extinction. 



Penhallow^ records some petrified wood from Cretaceous strata 

 in Alberta which he names Sequoia albertensis and regards as very 

 similar to the wood of Sequoia sempervirens, but the evidence in 

 favour of a reference to the existing genus is inconclusive. Eesin- 

 cells are scattered through the wood; the medullary rays have 1 — 2 

 bordered pits in the field, the broadly elliptical pore being generally 

 diagonal to the cell-axis. 



Tertiary wood from different localities in North America is 

 referred to Sequoia on evidence that is far from conclusive. Prof. 

 Jeffrey^ described a particularly well preserved piece of stem from 

 the Miocene auriferous gravels of the Sierra Nevada, near the 

 home of Sequoia gigantea, as Sequoia Penhallowi; though I am 

 informed that he is now inclined to refer the wood to the Abietineae. 

 In his account attention is called to certain features, e.g. the pitting 

 on the end-walls of the medullary -ray cells, the scarcity of xylem- 

 parenchyma, and the presence of vertical and horizontal resin- 

 canals, beheved to be traumatic, which are certainly suggestive of 

 abietineous affinity. Prof. Penhallow^ described two species from 

 Eocene beds in the North-West Territory as Sequoia Langsdorfii 

 and S. Burgessii, both of which were previously described by 

 Dawson but assigned by him to different positions. In the wood 

 beheved to belong to the plant which bore the well-known twigs 

 recorded by many authors as S. Langsdorfii resin-cells are numerous 

 and scattered and resin-canals are present only in a rudimentary 

 form on the outer face of the simimer-wood. The pitting of 

 the medullary-ray cells is not described. A pecuhar feature in 

 S. Burgessii, if the wood is correctly referred to Sequoia, is the 

 occurrence of two kinds of iriedullary rays, uniseriate and fusiform, 

 the latter containing resin-canals. No resin-canals occur in the 

 wood. Attention has been called (p. 171, fig. 712) to the abundance 

 of petrified stems in the Lower Tertiary deposits in the Yellow- 

 stone Park: some of these are named by Mr Knowlton* Sequoia 

 rmgnifi,ca. A few of the trunks reach a diameter of 6 — 10 ft. 



1 Penhallow (08) p. 83, figs. 1—6. 



2 Jeffrey (04). ^ Penhallow (03) pp. 41—46, figs. 2—8. 

 ' Knowlton (99) p. 761, Pis. civ., cv., ex., cxi., cxvii. 



