LITERATURE OP THE CONIFERS. 55 



firms of the Academy of Science of St. Louis, and others. In the 

 following pages, we have freely availed ourselves of the information 

 contained in these valuable papers. Within the last few years, characters, 

 as a means of classification and identification of species, have been sought 

 for in the anatomical structure of the leaves of the Firs and other 

 genera, One of the earliest investigators in this direction was T. Thomas, 

 who, hi 1865, published a treatise on the subject in Dr. Pringheim's 

 Jahrbuch IV. He was followed, in 1871, by C. E. Bertram!, of Paris, 

 who gave a more elaborate paper on the subject, in 1874, in the 

 Annulet ties Sciences Naturclles. The subject was taken up in the 

 following year, by Dr. W. R. Mac^ab, in the Proceedings of the Royal 

 Irish- Academy ; and in 1877, the same botanist published an exhaustive 

 paper in the same journal, pp. 673-704, entitled A Revision of the Species 

 of Abies, in which twenty-four species are described under Abies (Silver 

 Firs), and five others, under Pseudotsuga, viz., A. nobilis, A. magnified, 

 A. Douglasii, A. Fortune/, and another under the name of A. Davidiana, 

 said to be a native of Thibet, and allied to A. Fortune). The same 

 line of investigation has been pursued by Dr. Engelmann, of St. Louis, 

 Missouri, who observes that " highly important as the microscopic inves- 

 tigations of the leaf are, they have sometimes been relied on too 

 exclusively, disregarding the characters furnished by the reproductive 

 organs."* He cites, as instances, the Pseudotsuga section of Drs. 

 Bertrand and McXab, above mentioned. 



We have purposely reserved for concluding notice, although not the 

 latest in order of publication, the ConiferEe, in De Candolle's Prodromus 

 xvi., pars. 2 (1868), by the late Professor Parlatore, of Florence, 

 which is now generally regarded by botanists as one of the most 

 authoritative purely scientific expositions of the Order yet published. 

 In this work, the characters on which the tribes, sub-tribes, and 

 genera, are founded, are chiefly, if not solely derived from the organs 

 of fructification, the characters of vegetation being altogether subordinate 

 and relied on in framing specific differences only. Thus, the Linnsean 

 circumscription of Pinus is restored, and the divisions of the original 

 genus by Link and Carriere into five and six genera, are made 

 sectional; the dismemberment of Thuia and Cupressus by Endlicher, 

 and others, is retained; Siebold's Retinospora is altogether rejected, the 

 species being described under Chamsecyparis ; Philippi's Prumnopitys is 

 also rejected; the Linnaean Ginkgo (Salisb'uria) is restored, and a few 

 other changes of minor importance are also introduced, as will be 

 seen from the following synoptic table. 



It is scarcely necessary to add, except for the information of those 

 who are unacquainted with Parlatore's work, that it is one of the 

 most valuable contributions to botanical science of late years, and that 

 it is compiled in the Latin language, 



* Trans-. Acad., St. Louis, 1878. 



