16 IXTKODUCTIOX. 



Musk-rat, the Americixn Buffalo, Tree-P(ircupines, and the Turkey. 

 The Beaver, Reindeer (Caribou), Sheeji, ami Bears are types com- 

 mon to this and the PaUearctic Region. 



VI. The Neotropical Province, including the whole of South 

 America, Central America, and Southern Mexico, together with 

 the Antilles. Characteristic animals are the Platyrhine Monkeys, 

 Llamas, Peccaries, Cavies, Sloths, Ant-eaters, Armadillos, Trogons, 

 and Cura^sows. There is an absence of Insectivorous Mammals, 

 Goats, Antelopes, Oxen, Cranes, &e. The Opossums are common 

 to this and to the Nearctic Province. 



LeaA'ing the dry land, we find that even in the ocean animals are 

 not distril>uted at random, l>ut liave, on the contrary, a more or le.ss 

 definite range. Without entering at length into this very inter- 

 esting subject, two or three of the more inijiortant facts connected 

 with the distriljution of marine life in.ay be stated here. In the 

 first place, certain marine animals affect that portion of the sea- 

 shore which lies lietween tide-marks, and is therefore more or less 

 completely uncovered twice a-day by the retirement of the tide. 

 Technic.dly, naturalists call the tract between tide-marks the "Lit- 

 toral Zone" (Latin, litiix, the shore). In the second place, "we find 

 other animals which do not like to be uncovered by the retiring 

 tide, and which live, therefore, just below the limit of low water, and 

 usually extend their range till the sea becomes aljout fifteen fathoms 

 in depth. Within these linnts the great Tangle {La.-ii iimrin) flourishes 

 in jirofusion, and hence this is called the " Laminarian Zone." Be- 

 3'ond the Laminarian Zone are other regions of different depths, 

 which can usually be recognised more or less distinctly by the 

 animals Avliich inhabit them. Finally, by the researches of Car- 

 penter, Wyville Thomson, (iwyn Jeffreys, Wa'lic'i, Sars, Pourtales, 

 Agassiz, anil other observers, we know that the "deep sea" prop- 

 erly so called, extending from a depth of .'^lirt fathoms up to at least 

 3000 or 4000 fathoms, is tenanted Ijy a vast nund.)er of aiumals, 

 constituting a very remarkable and peculiar life-assendjlage. We 

 also know now, that, exce]it in very lindted depths, the distribution 

 of marine animals is conditioned not l)y the depth of the water, Ijut 

 by its ti'tniieratiirc. Similar forms of mai'ine life are thei'efore found 

 inhabiting areas in which the bottom-temperature is the same, irre- 

 spective of what the dejitli of the water may be. And it nuiy hajjpen 

 that two neighbouring areas of the seadiottom may be inhabited 

 by different assemblages of animals, in spite of their being close 

 together, jirovided one area is swept by a inrivnt of waim water, 

 whilst the other has its temperature lowered by the influx of a cold 

 curi'eiit. 



DisTitinrTiox in Time. — The distribution of ainmals in iiast 



