Physiography of the Isthmus of Choc. 373 
Section V. The Lowland.—Closely allied to section IV. are 
the lowlands with an east to west extent of about fifteen miles. 
The geological physiognomy of this belt differs from that of the 
isades only by having a more inclined surface. The up- . 
olding strata towards the west end of the section exhibit more 
or “i disturbed, often broken and isolated layers of tertiary 
rocks, 
Nature’s means for producing the most surprising results ap- 
ear often very trifling. Here a slight increase of the angle of 
inclination changes almost the whole physiognomy of the surface. 
the Truandé, before divided into endless branches and sweeping 
like a many-headed Hydra through the nocturnal forests below, 
tow gathers its waters into one bed. Its winding course is bor- 
dered by more elevated banks, which are crowned alternately by 
the growth of heavy timber or densely interwoven brushwork, 
or appear lined by patches of succulent Endogens of the orders 
of Musaceze, Amomacese and Graminez, whilst the whole seems 
to be seat all over with the rich garlands of a perpe 
ival, 
idese, decrease in a similar ratio as others increase. 
Similar changes take place in regard to animal life. Several 
Mouth of the Salado, a little tributary of the Truand6. This 
ty 3s also oryctognostically marked by a fossiliferous _ 
"orphic limestone? which in’ all probability will answer 
Section VI. The Table-land—At the western margin of the 
jowland a rocky terrace rises, the seep side of which faces east. 
xe the top of it the table-lands o See 
eta are placed. af he various strata consti- 
ane these table-lands are augitic (perhaps trappean) ing 
~~“? sttongly granular crystalline or compact amygdaloid or 
