282 ON THE GEOGRAPHICAL 



rallel of latitude, this continent, in breadth, hardly exceeds 

 one third of the eastern. 



It is not our purpose to examine in detail the geogra- 

 phical distribution of forms. In general, the intertropical re- 

 gions should be contrasted with the remainder of the globe, 

 and thus all forms will be either intertropical or extratropical. 

 — The Palmx, Scitaminex, Musacex, Bromeliacex, Jluran- 

 tiacex, Guttiferx, Sapotex, Piper aeex, Malpighiacex, Melasto- 

 mex, Meliacex, Sec. are intertropical forms. — The Rhododen- 

 dracex, Ericex, Saxifragex, Umbelliferx, Jlmentacex, Com- 

 ferx, Proteacex, Epacridex, Rosacex, Geraniacex, Caryophyl- 

 lex, Cistinex, Cruciferx, Ranunculaccx, fyc. are extratropical 

 forms. 



Again, the northern and southern regions of the globe may 

 be contrasted. — The Proteacex, Epacridex, fyc. are peculiar 

 to the southern ; the Cistinex, fyc. to the northern portions 

 of it. 



Descending from superior to inferior group, we observe a 

 continual tendency to become restricted to some one of the 

 above botanical regions : — to some of which, entire natural 

 orders are limited, and where orders are not, families or tribes 

 are : descending still lower, many genera are found to be pe- 

 culiar to each ; and even if a genus be not so far restricted, a 

 natural section of it, or some peculiarity in structure or habit, 

 is frequently confined to one region. These facts are deserv- 

 ing of the greatest attention : it is to be observed, however, 

 that from analogy of structure, a like relation to climate might 

 be expected. 



On the same principles, maps of the geographical distribu- 

 tion of quadrupeds, birds, reptiles, fishes, mollusca, Crustacea, 

 insects, &c. may be constructed ; each of which classes will re- 

 quire particular modifications. 



Thus, examining the distribution of land quadrupeds, we 

 observe that their range is not so much influenced by tem- 

 perature, as that of plants, and more so by the ocean : — un- 

 like the seeds of plants, they cannot pass a great extent of wa- 

 ter, while at the same time they roam through more degrees 



