94 
of the Eocene, sometimes a little below the 
ocean level, never far above. Geologic change 
has been at no time great enough to prevent 
the easy reentrance of the sub-tropic vegeta- 
tion, persistent in the United States at three 
points only—the Lower Colorado, the Lower 
Rio Grande, and the lower part of the “spruce 
pine,” and Pinus heterophylla sections of 
Florida. In each of these widely separated 
regions larger continental features tend to 
create and maintain melior climatic condi- 
tions. The Colorado cuts deep, and holds its 
valley protected from the cold. The gulf 
warms the low coastal strip markedly as far 
north as the mouth of the Rio Grande; and 
Florida, though flung well out to sea, so blocks 
the warmer gulf waters that the southern half 
has long held to the favorable mean of dry 
days, rain and warmth. Long coastal barriers 
afford further protection. 
Even a cursory glance at forest distribution 
in Florida serves to throw into relief the belts 
and regions of change of first concern. The 
upper half of Florida is still favorable to the 
“long leaf pine” (Pinus palustris), and now 
undergoes marked variation in its winter tem- 
peratures. Facing the Atlantic, this forest 
sharply gives way to the “spruce pine,” and 
not far below Vero the palmetto-cycad under- 
bush begins. Along the southern-western 
coast, is the region of “pine islands and cy- 
press straits,” as Bowman says, “even more 
monotonous than the east coast.” All the 
higher ground is invested by a Pinus hetero- 
phylla forest, with a nearly pure palmetto un- 
derbush, while the cycads also show a different 
facies. The Zamia floridana is rare in the 
open woods, although the Z. pumila grows 
more characteristically inside the mangrove 
fringes next the coast. 
The Vero man thus occurs near the border 
of the “spruce pine” (Pinus glabra) forest, 
with its striking and unique underbush of 
eyeads and bush palmetto (Zamia floridana 
and Sabal serrulata). The latter in places 
make up the underbush nearly in equal num- 
bers. But that this striking forest facies earl- 
ier extended to the north of Vero is probable; 
while in any case Vero lies within a region 
SCIENCE 
[N. S. Vor. XLVIITI. No. 1230 
locally characteristic for its old floral ele- 
ments, and of generally soft climate since the 
Eocene. 
Evidently the “ spruce pine” country ex- 
emplifies a pronounced type of the so-called 
“asylum” or isolated and persisting habitat 
subjected throughout long periods of time to 
the minimum of environmental change. Es- 
pecially the cats. earlier tended to drift to the 
south; and there the man of Vero found them 
when he reached that soft climate and em- 
ployed or developed arts admittedly recent. 
Seemingly too, the fossil plants and animals 
of Vero, after persisting beyond their geo- 
logically appointed time, were finally cut off 
by changes relatively slight. 
G. R. WieELAnD 
YALE UNIVERSITY 
SCIENTIFIC BOOKS 
Fossil Plants. By A. C. Szwarp. Oambridge 
Biological Series 1917. Vol. III., pp. xviii 
--- 656, 629 figs. 
The present volume, the third of Seward’s 
great work, Volume 1.having been published 
in 1898 and Volume 2 in 1910, is appropriately 
dedicated to the late Professor Zeiller, the dean 
of paleobotanists. It is to be followed by a 
fourth volume, which it is stated is already in 
press, and which will discuss the remaining 
gymnosperms—the great sroup of angiosperms, 
so abundant in the fossil record from the mid- 
Cretaceous to the present, apparently not com- 
ing within the category of fossil plants in the 
mind of a British botanist, which is quite in 
keeping with British tradition and practise. 
Volume 3 opens with a very satisfactory 
chapter devoted to a discussion of existing 
eyeads, largely an abstract of already pub- 
lished data. Then follow three chapters de- 
voted to the Pteridospermz. These are di- 
vided into three families—the Lyginopteride, 
Medullosee and Steloxylee, and are rather 
fully and very satisfactorily discussed. 
The remaining structural forms that are 
probably more or less closely related to the 
foregoing pteridospsrms are considered to rep- 
resent the following seven families: Mega- 
loxylee, Rhetinangier, Stenomyelee, Cyca- 
