358 



SCIENCE. 



[Vol. I., No. 13. 



PLANT-LIFE, PAST AND PRESENT. 



The (iprniiig locture of the second course of 

 'Saluiday li'cturos,' delivered at the National mu- 

 seum in Wa^liingion, was by Mr. Leslor F. Ward, 

 assistant gciildgisb U. S. geological survey, and honor- 

 ary curator of fossil plants to the museum; the sub- 

 ject being 'Plant-life of the globe, past and present.' 



The object of the li'ctuie was to give some account 

 of the jJiMgress which liao taken place tuward the 

 adoption of a truly natural system of botanical 

 classllicalion. After describing and comparing the 

 metbiids of Liune, of A. L. de Jussieu, of Adrien 

 de Ju^sieu, and of nioileru botanists, the lecturer 

 pointed out the objections which may be mnde to all 

 of these, and thoi presented the oulliiie of a system 

 which aimed to exclude tlie objectionable features, 

 and to accord with the results of the latest discoveries 

 in struct tu'al bolany, and especially with the teach- 

 ings i>f paleoiitoliigy, which he claimed to have been 

 too much ignored by botanists. The proposed sys- 

 tem was as tcillnws: — 

 fCalluliir. 



tJryptogar 



[Lcpidojiliytac . 

 { Cyt-adaccae. 



f FilicoB. 



( Rliizocarpeae. 



iEqlilsctincae. 

 Lycopodiucae. 

 LiL'ulatae. 



t Angiosxicni 



( Monocotyledons. 

 J i Apctalac. 



(Dicotyledons, j I'olypetalae. 

 ( Gaiiiopetalae. 



type which liave been found fossil at each geological 

 liorizoii, and also tlie most reliable estimates that 

 could be otitaincd of the miniber living at the present 

 time iir all parts of tlie world. It also showed the 

 percentage that each type formed of the total known 

 flora of each epoch. We give below a condensed 

 view of this chart, whicli is all we have space to 

 present. 

 Relative to this table, it should be explained, — 



1. That the (igures given for the li\ ing gymno- 

 sperins and dicoiyledoiis are, in round numbers, 

 those of Messrs. Bentham and Honker, as stated for 

 each genus and order in the 'Genera iilautartim,' 

 and wliieh are liere compiled, perhaps for the first 

 time. 



2. That the number of fossil species were collated 

 from a great number of sources; Sidiini|ier's 'Traite 

 de paleontidogie vegetale ' being the basi'*, supple- 

 mealed by data from all the more recent pulilications 

 which were accessible, and by some un|iulilishedilata. 

 Absolute completeness, however, was not claimed, but 

 only such substantial acciu-acy as was deemed sufiS- ■ 

 cieut for the purposes of the lecture. 



3. That under ' tertiary time' are included all the 

 beds from the quaternary to the middle cretaceous; 

 the latter being repi-esented in this country by the 

 Dakota group, ami \n Eiuope by the cenouiainan. 

 This is done because it is at the last-named horizon 

 that the dicotyledons first appear, and bccatise lliey ap- 

 pear lieie in sitcli extraordinary profusinu. Maiquis 

 Saporta lias also made the vegetable tertiary to begin 

 at this point.i 



The facts embodied in this table were further 

 graphically illustrated by two diagrams, prepared by 

 Ensign E. E. Ilayden, U.S.N. The first of these 

 showed, by means of accurately plotted curves and 



Number of known species of fossil and living planjts. 



The claims of this scheme as the nearest approach 

 yet made to the system of nature were supported, 

 Jor the most part, on paleonlolngical grounds. To 

 ■do this, nil elaborate chart was presented, giving the 

 geological liisinry of each of the principal ty]ies of 

 ■vegetation. This was in the form of a tabular 

 exhibit of the number of species belonging to each 



colored areas, the development of each type of vegeta- 

 tion through the several ascending strata, the breadth 

 of the areas at any epoch repiesenting the promi- 

 nence of the several types relatively to the entire 

 flora of that epoch. The other diagram consisted of 



• Le monde des plontes avant I'apparition de I'homme, p. 160. 



