306 Part III. Chapter 3. 
continent of past geologic times. Central America, the West Indies and northern 
South America formed in the Mesozoic period (certainly during the Jurassic 
and Cretaceous), a continental mass (Antillean continent) which was bounded 
by sea to the north and south’). This continent broke up at the end of the 
Cretaceous, the chief factor in its destruction being the formation of the Caribbean 
Sea, which connected with the Pacific Ocean during the lower Tertiary period 
across the submerged Isthmus of Panama. The northern remnant of this 
continent, consisting of the Greater Antilles and parts of present Central America, 
probably remained a unit up to the Eocene, for during the Eocene elevation, 
there was probably a landway from Cuba across the Bahama Banks to the 
Floridan area, so that we have an explanation of the exceptional association 
of Pinus cubensis and Serenoa serrulata (see Plate VI) in southern Florida, 
although it is well known that the northern ‚coniferae stop where the tropic- 
subtropic palms begin to occur. At the end of the Eocene, and during the 
Oligocene and Miocene, the connection between the Greater Antilles and the 
mainland was severed. But it was re-established toward the end of the Tertiary 
for before the close of the Tertiary period, the West Indian lands were more 
extensive than now, and the Greater Antilles were once continuous. The botanie 
evidence goes to show that there existed in the past (upper Cretaceous), an 
Antillean continental flora which developed as such when the West Indian is- 
lands, Central America and northern South America formed a distinct conti- 
nental area with rivers, mountains and plains covered with a tropic forest of 
great luxuriance which represents the progenitors of the present tropic flora. 
The table by HEMSLEY unquestionably points to such a conclusion. 
Proportional Distribution of Mexican and Central American Species in South 
America and the West Indies?). 
Western Eastern Western | Numbers of 
to böth th South South and South American | Er 
W 3 aba ‘| America America Eastern |types reaching 
estIndies |  Indies ; 
au: Säntk ‚ only included South | Mexico or Gua- 
Kinehnd (ineluding. | Venezuela | America | temala, but n a08 
Andine) only only the West Indies 
Polypetalae | 7 xy 190 55 v5 ee u 
Gamopetala E ei 182 112 129 65 8o 177 
Incompletae | 37 97 43 36 30 34 12 
Monocötyledoneae . 179 u: 64 99 103 183 
Gymnospermae... — 3 2 | 1 a. ; 
Totals 648 | 284 34. «| 261 429 698 | 
This table is only tentative, because so much remains to a done in elabo- 
rating the details of the distribution of species in the West Indies and the 
northern and eastern parts of South America. The western only are in 
I) See ante page 12 
2) HEMSLEY, er Biologia Centrali-Americana IV: 227. 18861888. 
Kr BE N ae 
wi er WR 
a ES Re Be ar 
