TRANSACTIONS OF THE SECTIONS. 107. 
the mined portion of the leaf, in which they descend to the ground, and therein 
change to the pupa state. Some mining larve move freely from one leaf to 
another; some only mine when they are young, feeding externally when about 
half-grown. Some of these mining larve have the usual complement of legs and 
rolegs; some have only 8 prolegs, the first pair of ventral prolegs being absent 5 
finally, some are entirely without legs, and these are difficult to recognize as Lepi- 
dopterous larve. 
On some Elucidations of the Geological History of North Africa, supplied by its 
lacustrine Fauna. By the Rev. H. B. Trisrram. 
On certain Facts on the Variation of Species, which point to Western Asia as the 
centre of Creation for the Palearctic Region. By the Rev. H. B. Tristram. 
On the Physical Geography of the Malay Archipelago. 
By Aurrep R. WALLAcE. 
This archipelago extends from the Nicobars on the north-west to San Cristoval, 
one of the Solomon Islands, on the south-east; and from Luzon, on the north, to 
Rotti, at the south-west angle of Timor, on the south; being an irregularly trian- 
gular area of 292° latitude, by 69° of longitude. For ethnological and other pur- 
oses the Malay peninsula, thengh a portion of the mainland, is included in this 
insular belt ; and analogous reasons induced the determination of the eastern limit. 
The author advocated the insertion in all future atlases of a special map of these 
islands, comprising so many races of man and such variety of physical phenomena 
as to entitle it almost to be regarded as the sixth great division of the globe. The 
immense number of active i distinct voleanos were then mentioned (the islands 
in which the former occur being unusually liable to earthquakes), as also the immense 
forests which, throughout a great portion of the archipelago, clothe even the 
loftiest mountains to their summits; while in other portions these give place to 
arid hills and plains scantily covered with scrub. The meteorological phenomena 
display similar contrasts, some of the islands experiencing the monsoons with the 
utmost regularity, while others show an inconstancy of climate resembling our own. 
But the most marked feature of the physical geography of the region is to be found 
in the fact that one large section is Tact by a very shallow sea with the con- 
tinent of Asia, while a similar submarine plateau unites another portion to Australia; 
the intervening belt of ocean being almost unfathomable. 
The author then subdivided the islands into—1l. Voleanic and Non-volcanic ; 
2. Forest Country and Open Country; 3. Well-marked Seasons and Undefined 
Seasons ; and 4. Western or Indo-Malayan Region, and Eastern or Austro-Malayan 
Region. 
a to the first, Borneo and Celebes formed two central masses, round which the 
volcanic islands are distributed in a band about 5000 miles in length, roughly con- 
forming to their outline, and comprising about fifty active volcanos. Throughout 
this entire length are to be found, at innumerable points, most convincing evidences 
of frequent upheavals and depressions of land, especially of upraised coral-reef. 
The island of Celebes, the great mass of Borneo, and the whole Malay peninsula 
have absolutely no volcano, active or extinct ; and there is a similar quiescent area, 
1000 miles wide, in the great island of New Guinea, where no volcano is known to 
exist nor earthquake to occur in an island estimated to contain 290,000 square 
miles, or 53,000 more than Borneo, hitherto regarded as, after Australia, the largest 
island in the world. Still further to the east occur a few small active volcanos. 
After describing the most striking peculiarities of climate and seasons, the author 
passed to the consideration of the geological formations and zoological products, 
and stated as a recognized fact that one portion of the archipelago is entirely 
Asiatic, while the remaining portion is quite as distinctly Australian. In support 
of this view, he briefly discussed the relations of the geographical distribution of 
animals and plants with geology; and claimed that the same changes in geological 
distribution of land and water, of which we have so many evidences in our pre- 
sent acquaintance with the constituents of the earth’s crust, are still going on. 
