No. 448.] 



AORTH AMERICA. 



ALES. 



palaeontological point of view, but also because of the important 

 bearing such exotic types have had in the sokition of questions 

 relating to descent. The methods adopted in these iinestiga- 

 tions have already been fully explained {38, p. 33 <■/ .sry.) and 

 further details at this time are uncalled for. 



In 1896 the work had reached such a point that it was 

 deemed desirable to make a preliminary statement of results. 

 This appeared in a paper published in the 'I'raiisaitioiis of the 

 Royal Society of Canada entitled the " (iencric Charac ters of 

 the North American Taxaceae and Conifera." in wliitli it was 

 shown that generic differentiations were possible. The diag- 

 noses and artificial key to the genera thus published, haw been 



species, with the most gratifying results ; and after se\en \ears 

 of severe testing, and in the light of more extended studies, they 

 are found to be substantially correct and reliable. 



The question of specific differentiation presented a far more 

 difficult problem, the solution of which has now been reached as 

 embodied in the present work. 



In the prosecution of these studies I have been under deep 

 and often constant obligations to helpful frientls working along 

 other lines. To Prof. C. S. Sargent of the Arnold Arboretum, 

 as also to Mr. Morris K. Jesup, President of the American 

 Museum of Natural History; Dr. N. L. Britton. Direct(M- of 

 the New York Botanical Gardens ; the late liaron lA-rd. \on 

 Mueller of Melbourne, Australia; Sir W. T. Ihistleton-Dyer, 

 Director of the Royal Gardens, Kew ; and to Mr. )•:. J. Max- 

 well of Montreal I am indeljted for much xaluable tyi)e 

 material. To Dr. B. \\. Fernow, formerly C hiet of the Bureau 

 of Forestry of the United States Department ot Agriculture, I 

 am under obligations for a large amount of material s]K'cially 

 selected with reference to testing the accuracy of diagnoses and 

 details of the key. To Mr. J. G. Jack of the Arnold Arboretum, 

 I am under particular obligations for the readiness with which he 

 has frequently responded to requests for material ot a trust- 

 worthy character, and his care in selecting a large series ot 

 specimens for testing purposes, which have contributed very 

 largely to the success of the final results. To my assistant. 



