Hhnuy and Flood — The Douglas Firs. 91 



Fii- and its var. ccicsia, yields an oil, consisting mainly of Beta-piiiene. Piniis 

 ponderosa, var. scopulomm, with small cones, a native of the Rocky Moun- 

 tains from eastern Montana southwards (llie region of Fsevdolsuf/a ylauca), 

 yields an oil consisting mainly of Alpha-pinene Pinus Jeffreyi, with very 

 large cones, occurring in southern California in the same region as Pscndot- 

 suga macrocarpa, yields an oil totally diffei'^nt from the two preceding trees, 

 containing 95 per cent, of heptane. The analogy in the distribution, size of 

 the cones, and different oils of the Douglas Fir and Yellow l^ine is very 

 striking. 



Notes by Pkofessor A. Henry. 



The microscopical details, and the drawings of the leaf-sections, flowers, 

 cone-scales, &c., are due. to Miss Flood. I am much indebted to Mr. C. T. 

 Bennett, B.sc, F.i.c, for his investigation into the oils obtained from the 

 Oregon and Colorado species. Help in providing material for study and in 

 other ways was obligingly rendered to me by Mr. J. S. Gamble, f.e.s., 

 Dr. Herbert Watney, Mr. W. E. Hiley, Mr. V. C. Le Fanu, Prof. Sir I. B. 

 Balfour, f.k.s , and Prof. W. G. Craib, m.a. 



Note added in Press." 



Note to p. 75. — With regard to the size attained by the Douglas Fir in 

 the southern Rocky Mountains, Wooton and Standley, "Flora of New 

 Mexico," state that the tree sometimes reaches a height of 200 feet, with 

 a diameter of 6 to 7 feet. This is probably an over-estimate. Mr. G. B.. 

 Sudworth has just written to me from Washington that eleven of the largest 

 trees measured in the Lincoln and Datil National Forests, New Mexico, 

 attained heights of 97, 130, 126, 111, 112, 114, 127, 137, 143, 128, and 

 150 feet. Some of these trees are considerably taller than any recorded 

 from Utah or Colorado, the highest measured in Utah being 119 feet, and in 

 Colorado, 115 feet. 



[Explanation of Plates. 



R.I. A. PROC, VOL. XXXV, SKCT. B. [N] 



