S86 Professor Owen's Address. 



"widely, diffused over the surface of the globe, because they are 

 suited to elevated tracts in tropical latitudes. There is, however, 

 another law which relates to the original appearance, or creation, 

 of plants, and which has produced different species flourishing 

 under similar physical conditions, in different regions of the 

 globe. Thus the plants of the mountains of South America 

 are of distinct species, and for the most part of distinct genera 

 from those of Asia. The plants of the temperate latitudes of North 

 America are of distinct species, and some of distinct genera, from 

 those of Europe. The Cactese of the hot regions of Mexico are 

 represented by the Euphorbiacese in parts of Africa having a similar 

 climate. The surface of the earth has been divided into twenty 

 five regions, of which I may cite as examples that of New Zealand, 

 in which Ferns predominate, together with generic forms, half of 

 which are European, and the rest approximating to Australian, 

 South African, and Antarctic forms ; and that of Australia, charac- 

 terized by its Eucalypti and Epacrides, chiefly known to us by the 

 researches of the great botanist, Robert Brown, the founder of 

 the Geography of Plants. 



DISTRIBUTION OF MARINE LIFE. 



Organic Life, in its animal form, is much more developed, and 

 more variously, in the sea, than in its vegetable form. Observations 

 of marine animals and their localities have led to attempts at 

 generalizing the results ; and the modes of enunciating these 

 generalizations or laws of geographical distribution are very analo- 

 gous to those which have been applied to the vegetable kingdom, 

 which is as diversely developed on land as in the animal kingdom 

 in the sea. The most interesting form of expression of the distri- 

 bution of marine life is that which parallels the perpendicular 

 distribution of plants. Edward Forbes has expressed this by 

 definino - five bathymetrical zones, or belts of depth, which he calls, 

 — 1, Littoral, 2, Circumlittoral ; 3, Median; 4, Infra-median ; 5, 

 Abyssal. The life-forms of these zones vary, of course, according 

 to the nature of the sea-bottom ; and are modified by those primi- 

 tive or creative laws that have caused representative species in 

 distant localities under like physical conditions, — species related 

 by analogy. Very much remains to be observed and studied by 

 naturalists in differnt parts of the globe, under the guidance of the 

 generalizations thus sketched out, to the completion of a perfect 

 theory. But in the progress to this, the results cannot fail to be 



