628 
BOTANY: W. TRELEASE 
cation, in which 183, or slightly over one-half of the whole, are figured 
for the first time. As in our immediate flora, white and red oaks occur 
in approximately equal numbers for the American flora as a whole: 
170 species of the former, and 179 of the latter, only 4 species of Proto- 
balanus being known. 
In variety as well as in actual number of species, the countries to the 
south of us are much richer in oaks than the Atlantic United States — a 
result to be expected from the more rugged configuration and greater 
meteorologic differences in those countries. The principal facts of the 
distribution of American oaks by countries are indicated in the following 
table. A very few species occur in more than one country, and there- 
fore are counted for both. 
COUNTRY 
LEUCOBALANUS 
PROTOBALANUS 
ERYTHROBA- 
LANUS 
TOTAL 
United States 
43 
2 
26 
71 
Mexico 
121 
2 
125 
248 
Central America 
20 
0 
35 
55 
South America 
0 
0 
4 
4 
Antilles 
1 
0 
0 
1 
Pacific Islands 
0 
1 
0 
1 
A glance at this table shows that, rich as the United States are in 
oaks, they are nearly equaled by the small Central American countries 
and far surpassed by Mexico. In the West Indies only a single species 
of white oak, doubtfully distinct from the live oak of our Gulf States, 
occurs, and this unquestionably derived from our mainland. In South 
America there are only four closely related species, of the red oak group, 
and these are clearly allied with some of the Costa Rican species. 
The genus Quercus is conceded to have existed in Cretaceous time 
though many Cretaceous and Tertiary fossils formerly referred to this 
genus are now placed in Dryophyllum, which is taken for the ancestral 
stock of the Fagaceae rather than of Quercus alone. Paleobotanists 
now admit 150 species of American fossil oaks pretty evenly distributed 
through the Cretaceous and the Eocene and Miocene divisions of the 
Tertiary. Few Pliocene fossils are known for North America; but in 
South America where a few others have been made known for the Ar- 
gentine, 4 species have been described from Pliocene deposits of equa- 
torial Brazil. It is noteworthy that the few existing South American 
oaks are confined to the Andes of Colombia. 
So far as I know, none of the earlier species survived from one to an- 
other of the periods of geologic time except for Q. furcinervis americana 
