180 FLORIDA GEOLOGICAL SURVEY-I3TH ANNUAL REPORT

hard limestone, where large enough to escape being swept by fire, and well shaded, as in hammocks and deep sinks and moutus of caves, usually have vegetation consisting mostly of ferns and mosses; but just why ferns should be partial to such places is not clear.*
 Red oak uplands. A very characteristic* type of vegetation around Ocala is the red oak woods (described in its proper place farther on). This is not confined to one particular type of soil, but attains its best development on a type a little different from that of the calcareous hainmocks or any other above described. In the soil survey of the "Ocala area" most of it is called "Gainesville loamy sand," though it does not seem to resemble closely anything around Gainesville. Mechanical analyses 21 and 22 and chemical analysis A probably represent phases of this type, and P certainly does, for it was specially selected for that purpose. Its most remarkable feature is the high percentage of phosphoric acid, and it is also pretty well supplied with potash and iron.
 Salamanders and gophers are rare or absent in this soil, perhaps because it is a little too rocky as well as too shady, but there must be other subterranean animals present, as in other fertile soils the world over. Red oak, sweet gum and hickory are the characteristic trees, and where this soil merges into the ordinary sandy uplands the, long-leaf pine comes in. A good deal of it, perhaps half, is cultivated, mostly in. corn, cotton or vegetables. Little or no fertilizer is used with the corn and cotton.

 MECHANICAL ANALYSES
 The following mechanical or physical analyses of central Florida soils and subsoils have been extracted from Bulletin 13 of the Division of Soils of the U. S. Department of Agriculture (A preliminary report on the soils of Florida, by Milton Whitney, 1898), and the soil surveys of the "Gainesville. area" (1905) ano "Ocala area" (1913). In the last named the localities and depths of the samples are not given, but they were obtained by correspondence with Prof. Whitney (who has been chief of the Bureau-formerly Division-of Soils since its beginning), and were used in the

 *For a description of one of the finest rock fern localities in our area see the papers referred to under the head of caves on page 163.