ISO Prof, Schouw on the Geographic DistrihuUon of Grsses. 
Hence it follows, that not one of these groups belongs exclu- 
sively to either the one or the other zone ; but that, on account 
of the proportionally greater number, the Paniceae^ Chloride^y 
Saccharmce^ Oryzeae^ Olyre^e^ and Bombiisaceae, may be regard- 
ed as tropical, Agrostidea^ Bromea^ and Hordeacecz^ as extra- 
tropical forms]; and that there is, consequently, a considerable* 
contrast between the forms of these two zones On the contrary, 
the difference between the various continents and degrees of lon- 
gitude is inconsiderable. Neither in the torrid nor temperate 
zone has any group in the Continent a perceptible preponderance 
over another. The result also appears to be the same, on com- 
paring the two hemispheres. We know, however, too little of 
the Southern to state this precisely. In respect of elevation, the 
distribution, according to the degrees of latitude, is very similar ; 
for, in the mountains of South America, the proportions of the 
larger groups are : 
0 — goo 
Toises, 
200—1100 
Toises. 
1100—1600 
Toises. 
Above 1600 
Toises. 
Paniceae, 
39 
33 
12 
1 
Agrostideae, - 
6 
10 
23 
2 
Bromeae, 
7 
7 
37 
8 
Saccharinae, 
16 
20 
20 
2 
Between the genera, the contrast is naturally greater, and ma- 
nifests itself not only according to the latitude, but also the lon- 
gitude. Thus in the torrid zone, the genus Paspalus has a de- 
cided preponderance in the new world. Most of the genera, 
however, especially the larger, for example, Panicum, Andro-^ 
pogon^ Chloris^ are every where nearly equal, those that are 
peculiar being generally not at all numerous. The generic dif- 
ference between North America and the temperate regions of the 
European Continent, is very small. In North America, however, 
a greater number of tropical forms appears. Between the two tem- 
perate zones also, the distinction seems to be by no means consi- 
derable. Of 36 species from the Cape, 30 occur in the temperate 
zone of the Northern Hemisphere; while, in other families. South- 
ern Africa has many peculiar to itself. In the extra-tropical part 
of New Holland, the greater number of genera are found also in 
the north (^bout f ds) ; and this appears to be still more the case 
