88 On Similarities in the 



geographical homologies. They are similar features in corre- 

 sponding localities. 



A remarkable group of similarities of this kind is to be 

 found in the arrangement of enclosed seas lying to the north- 

 ward of the three southern continents. To the northward of 

 South America there are the Gulf of Mexico and the different 

 basins of the Caribbean Sea ; to the northward of Africa there 

 are the Mediterranean with its different basins, and on the 

 north-east the Red Sea; and to the northward of Australia 

 there are the well-known seas of the Eastern Archipelago. 

 These seas are bounded on all sides by islands and insular 

 groups, and they are in continuous connection with two oceans, 

 the Pacific and the Indian. The African seas are bounded 

 entirely by continental land and communicate directly with 

 two oceans; but in the limited sense that one sea, the Red 

 Sea, communicates with the Indian Ocean by a single channel, 

 and the Mediterranean Seas with the Atlantic, likewise by 

 a single channel. Finally, the American seas are all in con- 

 tinuous communication with only one ocean, the Atlantic, 

 the continental barrier towards the Pacific being continuous. 



It is not unworthy of remark that the great depths (over 

 4000 fathoms) of the Atlantic and the Pacific Oceans occur 

 immediately to the northward of these groups of seas, and 

 in the western sinus of the northern portions of both oceans; 

 while the greatest depression of the continental land, the region 

 of the Dead Sea, is found similarly situated with regard to 

 Africa. The analogy here, however, does not hold good all 

 through, because it is a mere accident of climate that this 

 area does not form a large and not excessively deep fresh- 

 water lake. 



The enclosed seas just referred to lie on the margin of 

 debatable ground between the continental and elevated area 

 and the oceanic or depressed area of the earth's surface. The 

 bed of the great ocean, including in this designation the great 

 mass of water which surrounds the globe in its southern part 

 and extends its important branches into the Pacific, the Indian, 

 and the Atlantic oceans northwards, is necessarily a comple- 

 mentary feature in the earth's architecture as compared with 



