Geographical Distribution of Crastacea. 29 
From the survey already made, it is apparent, that the three 
. grand divisions of the seas and coasts adopted in the preceding 
| table, have very few species in common, and they correspond to 
a natural geographical arrangement. "They constitute three 
. kingdoms, to which two should be added, one for the Arctic 
| | Seas, and the other for the Antarctic. "'l'hese kingdoms are: 
I. 'The Occidental Kingdom, embracing the Atlantic and Pa- 
cific coasts of America to the frigid region, or some point in the 
subfrigid region. 
IIl. "The European Kingdom, extending from: Cape Horn (or 
Cape Agulhas) to the Shetlands inclusive, and embracing the ad- 
joining islands. 
IHE. 'The Oriental Kingdom, includiug the east coast of. Africa, 
the south and east of Asia, and the islands of the Indian and 
Pacific Ocean, exclusive of the American continent. 
IV. 'The Arctic Kingdom, including Norway, Iceland, Green- 
land, the Alascha Archipelago, and adjoining parts of the coasts 
|. ef America und Kamtschatka, with other Arctic lands. 
V. "The Antarctic Kingdom, embracing F'uegia, the Falk- 
lands, Southern New Zealand, and the lands or islands of the 
Antarctic Seas. 
It will not be understood that the torrid species in one of these 
kingdoms resembles the temperate more than do the torrid of an- 
—. ether kingdom ; for this is far from true, since the distribution 
of genera is to à great extent determined by temperature, as 
already shown. But taking the range of species of the kingdoms 
through, there is a striking difference between the kingdoms in 
species of the same temperature region or zone. 
Each of the first three kingdoms are naturally divided into 
three subkingdoms : a noríh, a middle, and a south, correspond- 
ing severally to the North ''emperate, ''orrid, and South 'T'em- 
perate zones of sea ternperature. "'l'he importance of these di- 
visions will be a subject of further remark beyond. 
'l'he summary of the results in the preceding table, presents 
some striking facts. 
— .. We observe, first, that there is a ratio of 1: 1:5 between the 
Maioids of the A and C divisions (that is between those of the 
Occidental and Oriental seas, as just explained), while the ratio 
ds about 1 : 43 for the Cancroids. So also, while the ratio es the 
A and B divisions together (Occidental and European) to C (Ori- 
ental) is for the Maioids, nearly 1:1, it is for the Cancroids, 
1:3. Here is a wide difference between the Occidental and 
Oriental seas as regards these groups. This last ratio is for the 
Corystoids nearly that for the Maioids, or more exactly, 1: 0/75; 
and for the Grapsoids it is 1:2; for the Leucosoids, 1:24. 
(The Arctic and Antarctic Seas are here merged in the other 
kingdoms, with which they are most nearly associated.) 
