348 BOTANICAL GAZETTE [ocTobER 
In this case there is clear evidence of the transportation of seeds by atmos- 
pheric currents over a distance of from 1200 to 1400 miles, and of their 
establishment in a new country. The number of naturalized species has now 
reached more than five hundred, and if the rate of increase of the last few 
lines as that of the indigenous flora, the number rapidly decreasing south- 4 
the Auckland district. Not more than two, most likely but one, of these will 
become naturalized on the stiff Wellington clay, while it is certain that fully 
one-third of them would have become established on the light scoria soil of 
the Auckland isthmus. Mr. Kirk draws a good distinction between displace- 
ment and replacement, and does not anticipate the absolute extermination of 
any large number of indigenous plants.—J. M. C. 
TWO RECENT paleobotanical reports of interest are those upon the fons = 
the Potomac formation, by Professor L. F. Ward, and upon the Tertiary” 
floras of the Yellowstone National Park, by Mr. F. H. Knowlton. Professor 
Ward discusses ® the Potomac formation in general, and then takes up 
detail the several floras into which it has been divided. These lower big’ } 
ceous floras present some striking features, aside from the ordinary jee 
paleobotanical material, Certain specimens are thought to be the remains : 
a species of Casuarina, which has been called C. Coviliei. The plate i aud 
senting a single specimen of this plant also contains the figures of two pte: 
species of Casuarina, and the resemblance certainly is striking; but W™ 
Ephedra and other jointed and fluted fossil genera in the background, rs 
Say nothing of Equisetum and its associates, the certainty of this oo a. 
not convincing. As the author remarks, “ it would certainly be an os a 
ing fact if it were proved that this anomalous type of vegetation sh 6% 
America during lower cretaceous time.” Even if the genus did nn 
however, it is not so clear that its association with Ephedra is . al Sgn 
cant of an intermediate position between gymnosperms and anging j 
that angiosperms have been derived from gymnosperms. The — ingl 
ing of the ferns are the species of Thyrsopteris, a living genus of bet 
‘9 Fifteenth annual report of the U. S. Geol. Survey, 307. 1895. 
