MARINE DISTllIBUTIOX. 69 



currence of purely pelagic animals. On the other hand, shal- 

 low-water marine animy^ls fall into assemblages characteristic 

 of definite areas or provinces of distribiitioti — that is to say, 

 though many species have a world-wide distribution, others 

 occur only in particular localities, and certain geographical 

 areas are marked by the existence in thi^m of a number of 

 such peculiar species. The basins of the Pacific, the Indian 

 Ocean, the Atlantic, the Mediterranean, and the Arctic seas, 

 are thus especially characterized ; and even limited areas of 

 these great geographical divisions, such as the Celtic, the 

 Lusitanian, and tlie Australian, have their peculiar features. 



But, though the shallow-water mjirine faunj\3 thus follow 

 the broad features of physical geoginphy, and though, within 

 each great province of distribution thus marked out, temper- 

 ature and other physical conditions have an obvious inlluence 

 in determining the range of species ; yet, on comparing any 

 two great areas together, dill'erences in climatal conditions 

 are at once seen to be inadequate to account for the diller- 

 ences between the faunae of the two areas. Climate in no 

 way enables us to understand why the Trigonia^ the penrly 

 I^autilus^ the Cestracion, the eared seals, and the penguins, 

 are found in the Pacific and not in the Atlantic area ; ^ nor 

 why the Cetacea of the arctic and antarctic regions should be 

 as dillerent as they are. When we turn to the distribution 

 of land-animals, the boundaries of the provinces of distribu- 

 tion correspond neither with physical features nor with cli- 

 matic conditions. Mammals, birds, reptiles, and nmi)hibians, 

 are so distributed at the present day as to mark ont lour great 

 areas or provinces of distribution of very unequal extent, in 

 each of which a number of characteristic types, not found 

 elsewhere, occur. These are : 1. 'i'he Arctogaal, including 

 North America, Europe, Africa, and Asia as far as Wallace's 

 line, or the boundary between the Indian and the Papuan 

 divisions of the Indian Archipelago ; 2. The Aifstrocohan- 

 bian, comprising- all the American Continent south of Mexico; 

 3. The Australian^ from Wallace's line to Tasmania ; 4. The 

 Novozdanian^ including the islands of New Zealand.^ 



J PcnfTuins arc found at the Cape of Good Hope and at the Falkland Islands, 

 but not in tlic nortiicrn jnarts of tlie wci-t coast of AlVica, nor cf tlic caet coast 

 of South America. In the Pacific they stretch nortli to the Papuan and Peru- 

 vian coasts. 



2 On tlio classification and distrihution of the AUdoromorphm and Hetero- 

 morpha' : ProcccdiuiTs of the Zorlofjical Society, 18fi8. Sclater on the " Geo- 

 p^rapliical l>isti-il)ution of Birds," Ibid., vol. ii. ' I'uclieran, " Kcvue et Ma,<?asin 

 dc Zoologic," lb65. Murray, " The Geographical Distribution of Mammals." 



