384 HarPER: BOTANICAL CROSS-SECTION OF MISSISSIPPI 
Assuming the above figures to represent correctly the relative 
abundance of the species, less than 2% of the woody plants (i. e., 
individuals, not species) are evergreen. The significance of this 
fact will be discussed farther on. 
The oaks in this region, as in the ‘“‘delta’”’ region to be de- 
scribed below, are rather puzzling, especially to one who has 
never seen them before and has no opportunity to stop and 
examine them closely in the light of descriptions or specimens. 
Dr. Hilgard* has described some curious forms of oaks in this very 
region, which ought to be investigated by a competent taxono- 
mist. The comparatively large number of herbs, and the occur- 
rence of a few genuine prairie species, such as Ambrosia bidentata, 
Silphium laciniatum, S. terebinthinaceum, S. perfoliatum, Mesadenia 
tuberosa, and Polytaenia Nuttallu (the last three seen only once, 
and therefore not listed), are reminders of the prairie conditions 
that once existed in this region. 
Pontotoc Ridge. The next younger formation in Mississippi 
is the Ripley, the uppermost division of the Cretaceous. Its 
strata are more sandy and therefore less easily eroded and dis- 
solved than the Rotten Limestone, and they give rise to a belt of 
hills, rather rugged for the coastal plain, known in Mississippi 
as the Pontotoc Ridge. According to Dr. Hilgard’s analyses its 
soil contains 0.17-0.28% of lime, 0.15-0.37% of potash, and 
0.08-0.11% of phosphoric acid; or approximately half as much of 
these important materials as in the prairie belt.t The Ripley 
formation and its corresponding topography are wanting in the 
latitude of Columbus and Greenville, but on the return trip I 
traversed it for about 15 miles, between New Albany and Sherman. 
Although the soil of the Pontotoc Ridge is perceptibly less 
fertile than that of the neighboring prairies, it is mostly under 
cultivation now, and one does not get a very accurate idea of its 
native vegetation by merely crossing it once on a fast train. In 
the following list the numbers are omitted, because they would 
be too small to have much significance. 
* Soils 491, 404, 498-502. 
} For descriptions of this part of Mississippi see Hilgard, Geol. & Agric. Miss. 
83-92. 1860; U. S. Tenth Census §: 221-223, 292-294. 1884; and the U. S. soil 
survey of Pontotoc County by Bennett and Winston, 1907. 
