ol4 REPORT OF THE HARVARD AFRICAN EXPEDITION 
very good. Analyses of this soil, according to Martin,! demonstrate the follow- 
ing as the more important substances: 
Pl Onsen. wok She pak OU ela ote: Se Roney es 6.9-31.9% 
1 |G SA en PRU tae ht SSS es emer Avge te 31.7-87.1% 
Fe.Q3 Sty Pe ET EAE ge eo oe NL Ae Oe 3.4-11 8% 
Oe ee nce bu te a eee ee traces—2.5% 
While the samples were taken in Sierra Leone, nevertheless they are indicative 
of conditions found in Liberia. 
Although lateritic soil is predominant in the regions visited, there are excep- 
tions. Along the seacoast, forming a narrow belt, the soil in the low ‘almost 
level stretches consists mostly of sand that has been either deposited from the 
seas as is evidenced by the presence of barrier beaches or else has resulted from 
the extreme weathering of laterite. At all events, there is a definite flora, es- 
pecially of the herbaceous types, that appears to be correlated with the coastal 
sand belt. Sandy soil, however, is not confined to the coast, for in the interior 
one frequently encounters stretches of almost pure sand deposited in valleys. 
It seems quite probable that such sand deposits are the result of weathering and 
erosion. Occasionally there are outcrops of sandstone so that this can also 
explain the presence of some of the sand deposits. Frequently also, the soil is 
gravelly but in such cases the lateritic soil of which it forms a part, is so abundant 
that it is difficult to discover any influence on the nature of the flora. Other 
factors influencing floral distribution such as drainage, and salinity will be con- 
sidered later on in the text as occasion demands. 
Brief mention should be given to the geographic relations of the flora of this 
region to that of others. Many of the species collected are found throughout 
the range of the rain forest belt, extending as we have said, from somewhat north 
of Sierra Leone to the Cameroons, and eastward to the northern part of the 
Belgian Congo. In spite of the extensive contacts such a belt provides, there 
are among the widespread species, also some of more limited range that appear 
to be confined to Liberia or at least to Liberia and bordering countries. There 
is an element in the flora derived from South America, that is illustrated by 
the presence of the cactus Rhipsalis, and Maschalocephalus Dinklagei, the sole 
member of the Rapataceae representing this South American family in Africa. 
In the following account of the botanical aspects of the visit to Liberia, the 
writer has confined his observations only to those regions visited by him lying 
between the St. Paul and the Farmington rivers as indicated on the accompany- 
ing map. Only a very general account can be given since a large number of 
species, and even families of phanerogams, and all but a few of the fungi still 
remain undetermined. 
MOonroVIA AND VICINITY 
Monrovia, the point of debarkation and the source of the first fruits of 
collecting, is situated on a peninsula formed by the mouth of the St. Paul River 
on the one side and the ocean on the other. This peninsula for the most part is 
1 Martin, F. J: Losses on igniting soil fractions. Journ. Agr. Sci. 18:123-130. 1928. | 
