DISCUSSION BY C. A. WHITE AND L. F. WARD. 15 



Karpinsky in Russia, and Gemmellaro in Sicily. They show that a large proportion 

 of the faunal types which have long heen regarded so characteristic of the Mesozoic 

 began their existence before the close of Paleozoic time, and that these forms often 

 constituted members of faunas which embraced well-known Carboniferous species. 

 They also show, what we ought always to have expected to find, that upon the 

 confines of systems and formations there was necessarily a faunal gradation from 

 the earlier to the later divisions. 



Professor Lester F. Ward spoke as follows : 



I am glad to observe that the invertebrate and vertebrate paleontologists are be- 

 ginning to discover that the evidence of the fauna relative to the age of the deposits 

 of the southern hemisphere is not as harmonious as was originally supp< ised. With 

 regard to the plants, we are not of course as yet in condition to make any very broad 

 generalizations, but we have at least reached a point where we can propose a 

 hypothesis which, however much it may require to be modified, is certain to lead in 

 the direction of ultimate truth. This hypothesis is briefly this : At an early period 

 in geologic history there flourished in both hemispheres a vegetation which is 

 commonly understood as the Carboniferous flora, consisting of the lepidophytes, 

 calamites, and marattiaeeous tree-ferns, together with the genus Cordaites, alone 

 representing the phanerogams. In the southern hemisphere, in addition to this 

 Carboniferous flora and contemporaneous with it, there existed another and quite 

 different type of vegetation which we now call the Glossopteris flora. When the 

 great Permian glaciation of those regions came on, the true Carboniferous flora proved 

 incapable of supporting the lowered temperatures and succumbed. The Glossopteris 

 flora, on the contrary, consisting largely of the primordial representatives of higher 

 types of vegetation — cycadaceae, conifers, etc. — survived, persisted, and underwent 

 great modification. In its modified form it came at length to constitute the now 

 well-known Mesozoic flora of Australia and India, the types of which can be traced 

 back into the Paleozoic. This Mesozoic flora of the southern hemisphere, already 

 found in southern Africa and in South America, which also contain true Glossopteris 

 types, not only persisted long in these regions but migrated northward and is now 

 found, altered it is true but distinctly recognizable, throughout vast areas of the 

 northern hemisphere. From India it found its way to Cochin-China, China proper, 

 and Japan, as also to Persia, Asia Minor, and the Caucasus. In South America it occurs 

 in the Argentine Republic and Chile ; it also reappears in the state of Honduras and 

 in Mexico, both in the central part and also in Sonora along the Rio Grande. From 

 the last-nan led locality, and probably as an eastern extension of the same area, we 

 find it occupying the great arid plains of Arizona and New Mexico— the Shinarump 

 formation of Powell. It again conies forth along the Atlantic slope in the; Con- 

 necticut valley, in New Jersey, Pennsylvania and Maryland, and on southward 

 through the coal fields of Virginia and North Carolina. In Europe it is this same 

 greal .Mesozoic flora which has been so abundantly exhumed and brought to light 

 in Franconia (Bavaria), in Brunswick, in southern Sweden, and in many parts of 

 France, while to it also belong the celebrated upper Triassic beds of Raibl in ( larin- 

 thia,of l.uu/. in Austria, of Stuttgart in Wurtemberg, and of Nine Welt near Basle 

 in Switzerland. However much these floras may differ specifically, they all have 



the same general Eacies, and bear evidence of having descended with modification 



from the original Glossopteris flora of Carboniferous age, which must then have 

 covered land areas in the far south much greater than those of I lie present day. 



This paper will be published in the American Naturalist. 



