1818.] Neighbourhood of the River Zaire. 21& 



from this proportion ; and these do not seem all of them to depend 

 merely upon variations in temperature. We are informed that 

 the proportion of the Congo collection, which is also that of the 

 equinoctial part of New Holland, is found to exist both in North 

 and South America, as well as in Van Diemen's island, and in 

 the south of Europe. 



In Prof. Smith's herbarium, the acotyledonous or cryptoga- 

 mous plants are to the phaenogamous as about 1 to 18; and 

 there is reason, from different considerations, to suppose that 

 this is not far from the actual proportion. In the parts of New 

 Holland that are near the equator, the numbers are as about 

 1 to 13 ; but the proportion is very different in the different 

 tropical regions ; and this difference seems to depend, in a consi- 

 derable degree, upon the elevation of the district ; near the 

 shores the proportion may be stated to be about 1 to 15 ; while 

 in mountainous countries it is about as one to five. 



The herbarium from Congo contains specimens from 87 of 

 the natural orders, but more than half of them belong to nine 

 orders only, being those which have their greatest number of 

 species between the tropics, or at least in the lower latitudes ; 

 the orders are, the Filices, Gramineae, Cyperaceee, Convolvu- 

 laceae, Rubiaceae, Composites, Malvaceae, Leguminosse, and 

 Euphorbiaceae. 



After describing in detail the plants in Prof. Smith's herba- 

 rium that belong to the different natural orders, Mr. Brown 

 proceeds to compare the vegetation of the line of the river 

 Zaire with that of other equinoctial countries, and with the 

 various parts of the continent of Africa and its adjoining islands. 

 With respect to the other parts of the west coast of Africa, it 

 appears that from the river Senegal in 16° N. latitude to the 

 Zaire in 6° S. latitude, there is a remarkable uniformity in the 

 vegetation, not only with respect to the natural orders and 

 genera, but even as far as respects the species. The same 

 similarity seems also to exist in the cultivated as well as in the 

 indigenous plants. On the banks of the river, as far as the 

 expedition proceeded, the principal articles of vegetable food 

 were found to be Indian corn, cassava, two kinds of pulse, and 

 ground nuts. The most valuable fruits were plaintains, papaws, 

 pumpkins, limes and oranges, pine apples, tamarinds, and a 

 fruit called safa, like a small plum. A very valuable plant along 

 the whole line of coast is the oil palm, elaeis guineensis, from 

 which the best kind of palm wine is produced. It appears also 

 that the common yam, capsicum, two species of the sugar cane, 

 and tobacco, were cultivated in particular spots. It is worthy 

 of remark, that the greatest part of these cultivated plants are not 

 natives of the country, but have been introduced from other 

 parts of the world, maize, cassava, pineapple, papaw, capsicum, 

 and tobacco, were probably introduced from America, while 

 the lunana, lime, orange, tamarind, and sugar cane, are probably 

 of Asiatic origin. In determining to what country we are to 



