Ch. XV.] UPPER MIOCENE— SIWALIK HILLS. 277 



canine, the Machairodus among* the former, also hyaenas, and a suburs • 

 ine form called the Hyaenarctos, and a genus allied to the otter (Enhy- 

 driodon), of formidable size. 



The giraffe, camel, and a large ostrich may be cited as proofs that 

 there were formerly extensive plains where now a steep chain of hills, 

 with deep ravines, runs for many hundred miles east and west. Among 

 the accompanying reptiles are several crocodiles, some of huge dimen- 

 sions, and one not distinguishable, says Dr. Falconer, from a species 

 now living in the Ganges ( 0. Gangeticus), and there is still another 

 saurian which the same anatomist has identified with a species now 

 inhabiting India. There was also an extinct species of tortoise of gi- 

 gantic proportions [Colossochelys Atlas), the curved shell of which was 

 twelve feet three inches long and eight feet in diameter, the entire 

 length of the animal being estimated at eighteen feet, and its probable 

 height seven feet. 



That some of the reptiles should, as well as many of the shells, 

 have survived from the Upper Miocene to the human epoch, need 

 scarcely excite surprise, for we have no reason to assume that the 

 mean temperature of India in the Miocene period differed materially 

 from that which now prevails ; although the climate must have been 

 greatly modified by the revolution which has since occurred in the 

 physical geography of the district. The heat may be as great now, 

 if not greater, than when the Sivatherium and Chalicotherium 

 flourished. 



Numerous fossils of the Siwalik type have also been found in 

 Perim Island, in the Gulf of Cambay, and among these a species of 

 Dinotherium, a genus so characteristic of the Upper Miocene period 

 in Europe. 



Atlantic Islands. — Something will be said of the Upper Miocene 

 formations of marine origin in Madeira, the Canary Islands, and the 

 Azores, when I speak, in the thirty-first chapter, of the volcanic rocks 

 of those countries. 



Older Pliocene and Miocene formations in the United States. — Be- 

 tween the Alleghany Mountains, formed of older rocks, and the Atlan- 

 tic, there intervenes, in the United States, a low region occupied prin- 

 cipally by beds of marl, clay, and sand, consisting of the cretaceous 

 and tertiary formations, and chiefly of the latter. The general eleva- 

 tion of this plain bordering the Atlantic does not exceed 100 feet, 

 although it is sometimes several hundred feet high. Its width in the 

 middle and southern States is very commonly from 100 to 150 miles. 

 It consists, in the South, as in Georgia, Alabama, and South Carolina, 

 almost exclusively of Eocene deposits ; but in North Carolina, Mary- 

 land, Virginia, Delaware, more modern strata predominate, which, 

 after examining them in 1842, I supposed to be of the age of the 

 English Crag and faluns of Touraine.* If, chronologically speaking, 



* Proceed, of the Geol. Soc, vol. iv. Pt. 3, 1845, p. 54V. 



