Professor Owen's Address. 387 



practically most valuable. A shell or a sea-weed, whose relations 

 to depth are thus understood, may afford important information or 

 warning to the navigator. To the geologist the distributions of 

 marine life according to the zones of depth, has given the clue to 

 the determination of the depth of the seas in which certain forma- 

 tions have been deposited. 



DISTRIBUTION OF TERRESTRIAL LIFE. 



Had all the terrestrial animals that now exist diverged from one 

 common centre within the limited of period a few thousand years, 

 it might have been expected that the remoteness of their actual 

 localities from such ideal centre would bear a certain ratio with 

 their respective powers of locomotion. With regard to the 

 class of birds, one might have expected to find that those 

 which were deprived of the power of flight, and were adapted to 

 subsist on the vegetation of a warm or temperate latitude, would 

 still be met with more or less associated together, and least dis- 

 tant from the original centre of dispersion, situated in such a 

 latitude. This, however, is not only not the case with birds, but 

 is not so with any other classes of animals. The Quadruman a 

 or order of apes, monkeys and lemur, consist of three chief divi- 

 sions — Catarhines, Platyrhines, and Strepsirhines. The first 

 family is peculiar to the " Old World " ; the second to South 

 America ; the third has the majority of its species and its chief 

 genus (Lemur), exclusively in Madagascar. Out of twenty-six 

 known species of Lemuridse, only six are Asiatic, and three are 

 African. Whilst adverting to the geographical distribution of 

 Quadrumana, I would contrast the peculiarly limited range of the 

 orangs and chimpanzees with the cosmopolitan power of mankind. 

 The two species of orang (Pithecus) are confined to Borneo and 

 Sumatra ; the two species of chimpanzee (Troglodytes) are limited 

 to an intertropical tract of the western part of Africa. They 

 appear to be inexorably bound by climatal influences regulating 

 the assemblage of certain trees and the production of certain 

 fruits. Climate rigidly limits the range of the Quadrumana lati- 

 tudinally ; creational and geographical causes limit their range in 

 longitude. Distinct genera represent each other in the same lati- 

 tudes of the New and Old Worlds ; and also, in a great degree, 

 in Africa and Asia. But the development of an orang out of a 

 chimpanzee, or reciprocally, is physiologically inconceivable. The 

 order of Ruminantia is principally represented by Old World 



