On the Geography of Insects. 677 



The specimens of chalk wh'.ch were examined contained 

 alnmen and oxide of iron in small proportions ; and it is a 

 curious fact that these substances, as well as the silex, exist 

 in several crystallised forms of carbonate of lime in the same 

 proportions as in chalk. 



Though I am far from believing that these remarks can lead 

 to any conclusive result, yet I trust they are sufficient to ren- 

 der it improbable that subsidence has been the principal ac- 

 tion by which the flint beds have been formed. I scarcely 

 need add that the nature of the organic remains observed in 

 the flints render it quite impossible that they can be of igne- 

 ous origin.— G. O. Rees, M.B., F.G.S., %c.—59, Guildford 

 St., Russell Square, Nov. Uth, 1838. 



Note on the Geography of Insects. — Considering the globe 

 as two basins of water, each mostly surrounded by a bank of 

 land, the shore of each basin has or has had its peculiar race 

 of beings from man downwards, but in this note I allude on- 

 ly to insects. The lesser basin comprises the Atlantic Ocean, 

 and leaving Greenland, where nature meets in one animal 

 life, diverges more and more as we go southward, through 

 Europe on the one side, and through North America on the 

 other. In Africa and in South America the difference is still 

 greater; but at the Cape of Good Hope and in Patagonia the 

 mutual resemblance again grows stronger, thus forming a 

 continued series round the basin. The forms of insects on 

 the one side have corresponding forms on the other side in 

 the same degree of latitude, which is varied, however, by the 

 nature of the country ; but the likeness is much less than in 

 those on the line of longitude at an equal distance on either 

 side of the equator, where the sea hardly divides the land. — 

 A continued chain of links might be found by proceeding 

 from Canada, and stretching over the heights of the moun- 

 tains, and descending to the ocean at Cape Horn ; and again 

 on a smaller scale, beginning at a lower latitude, and taking 

 a less elevation on the mountains : and the same on the op- 

 posite coast. 



The other basin, forming the Pacific Ocean and the Indian 

 Sea, is much larger, and its natural history is less known. It 

 is bordered by the chief mountains of the earth, which, in 

 America, extend from Chili to the Aleutian Isles, and in Asia 

 comprise the Japanese, Himalayan, and Caucasian moun- 

 tains ; and in Africa, Mount Atlas and the Mountains of the 

 Moon and Lupata, and rise eastward in Madagascar, the Mau- 

 ritius, Sumatra, &c. There is a general likeness among the 

 insects of the land from Madagascar, along the shores of the 



