The northern-part of British Honduras, between the Rio Hondo and the Rio Nuevo, consists of an almost level plain, having an area of nearly 1,000 square miles. The soil is a vegetal humus; varying from a few inches to several feet in depth, the average depth being about 2 feet; beneath this is a stratum of marly limestone, outcrops of which are found in many places. The southern part of Yucatan, which, unlike the northern part, is comparatively well watered, is also flat, though a few small hills are found along the northern bank of the Rio Hondo, commencing about 50 miles from its mouth (fig. 1). Most of the land along the rivers is swampy, producing only reeds, coarse grasses, and mangrove trees. Beyond the swamp country are found "cuhun ridges," consisting of river valleys or depressions in the surface which have become filled with alluvium brought down by the rivers from the interior, forming an exceedingly rich soil suitable for the cultivation of maize and nearly every tropical product. It is upon these "cuhun ridges" that most of the mounds and other relics of the ancient inhabitants are found and that nearly all the villages of the modern Indians are built. Large tracts of what is known as "pine ridge" are scattered throughout this area; these are level or slightly undulating plains covered with gravel and coarse sand—exceedingly poor soil, producing only wiry grass, yellow pines, and small pimento palms. On these "pine ridges" Indian mounds are hardly ever found, nor do the Indians of to-day build villages upon them except in rare instances and for special local reasons. With the exception of the extreme northern part, nearly the whole of this area is well watered by rivers and streams, while scattered throughout it are numerous lagoons and lakes, the largest of which is the Bacalar Lagoon.