L. F. Ward — Fossil Dicotyledonous Leaves. 371 



It being evident that the mere form or outline of leaves does 

 not furnish the characters required these were sought in the 

 disposition of the fibro-vascular bundles commonly called the 

 nervation. A. P. DeCandolle in 1827 had classified leaves 

 according to their nervation as an important fact or in vegetable 

 organography, but vegetable paleontologists had not yet made 

 use of nervation for the identification of fossil leaf-prints. 

 These were all grouped together by Sternberg under his name 

 of Phyllites and his successors had been content to follow in his 

 footsteps. 



In 1838 Dr. Gr. Bianconi published an important paper on 

 this subject in the ISTuovi Annali delle Scienze naturali of Bo- 

 logna (Ann. I, torn, i, p. 343) in which he made a direct appli- 

 cation of the nervation to the study of fossil leaves. 



Two years later Bossmassler's " Yersteinerungen des Braun- 

 kohlensandsteins aus der Gregend von Altsattel in Bohmen " 

 appeared, in which a large number of such leaves are very 

 carefully figured. Bossmassler suggested, but did not adopt, 

 the plan of calling such plants by generic names composed of 

 the name of the genus of living plants presumed to be nearest 

 related, with the old word phyllites appended as a termination, 

 for example, Daphnophyllites for leaves resembling Daphne, etc. 

 "In this way," he says, "all possible repetition of a name 

 already in use would be avoided, we should recognize the name 

 as belonging to the ancient world, and they would announce 

 themselves as the names of leaf-genera." 



Brongniart (Prodrome, p. 209) had set the example of call- 

 ing some of these leaf impressions by the names of living gen- 

 era, and this was followed to some extent by Dr. Alexander 

 Braun in determining the well-preserved specimens from the 

 Oeningen beds, and more extensively by Dr. Franz linger in 

 studying those of Eadoboj, Parschlug and Bilin. In January, 

 1852, Leopold von Buch submitted to the Eoyal Academy of 

 Sciences at Berlin (Monatsbericht, 1852, p. 42) an important 

 paper on the nerves of leaves and the laws of their distribution, 

 which may have furnished the impetus for Baron von Bttings- 

 hausen's extensive and fertile researches in this line which be- 

 gan to be published in 1854, and in the prosecution of which 

 he has availed himself so successfully of the art of nature- 

 printing, or physiotypy. These researches and their constant 

 application to the identification of fossil plants are too well 

 known to require mention here, as are also those of the late 

 Dr. Oswald Heer in making known the fossil floras of Switzer- 

 land and the arctic regions. 



These investigators and their able contemporaries, Saporta, 

 Lesquereux, Engelhart and others have described a vast num- 

 ber of species from leaves alone and referred them to living 



