40 D. Prain — Flora of Narcondani and Barren Island. [No. 2, 



a level one, for it slopes so gradually northwards that, as it passes into 

 the Bay proper, its depth is still 1400 fathoms. No such clear delimita- 

 tion exists between Sea and Bay ; the plain that forms their common 

 floor still slopes gradually upwards towards the north till, in the neigh- 

 bourhood of Lat. 20° N., the edge of the shelf of the Grangetic Delta is 

 reached. 



The southern edge of the floor of the Sea of Bengal may, in spite 

 of its depth of over 2000 fathoms, be taken as, in a sense, the margin 

 also of the continent of Asia, for there is more than the rapid increase 

 of slope towards the bottom of the Indian Ocean to characterise it. To 

 the west it coincides with that remarkably abrupt terrestrial elevation 

 which results in the islaud of Ceylon, off the south-west coast of which 

 island, less than 40 miles from the Basses, the ocean depth of 2300 

 fathoms is reached. To the east a precisely similar terrestrial eleva- 

 tion, though of smaller size and much less height, is met with. Just as 

 Ceylon lies, a pear-shaped eminence, to the east of Lon. 80° B., so to the 

 east of Lon. 90° E. lies the pear-shaped eminence known as Carpenter's 

 Ridge,* a terrestrial mass that rises from a depth of 2300 fathoms in 

 Lat. 5° N., till in Lat. 6° N. and Lon. 90° 30' E., it reaches a point 

 which carries only 1380 fathoms. The ' thick end' of the pear in both 

 cases faces the south, and just as the ' stalk,' in the case of Ceylon, tails 

 north-westward into the Indian Peninsula, the ' stalk,' in the case of 

 Carpenter's Ridge, tails north-eastward into Middle Andaman. There 

 are these differences between the two ; the connecting ridge between 

 Ceylon and India carries nowhere more than 8 fathoms, that between 

 Carpenter's Ridge and the Andamans carries 1600 fathoms, while the 

 highest point of Carpenter's Ridge is as much beneath as the highest 

 point in Ceylon is above sea-level. 



The third area (c) is the land-locked seaf, bounded on the west by 

 the Andamans and Nicobars, on the north by the Irrawady Delta, on 

 the east by Tenasserim and Kedah, and prolonged south-eastward into 

 the Straits of Malacca, between Sumatra and the Malay Peninsula. 

 This sea is not, as a rule, distinguished by any general name, though 



* Alcock : Annals and Magazine of Natural History, ser. vi., iv., 377. 



t Carpenter : Records of the Geological Survey of India, xx, 48, had proved, as 

 conclusively as it is possible in the absence of actual soundings to prove, that this 

 body of water must be separated from the Sea of Bengal by a ridge nowhere 

 deeper than 760 fathoms, the shallowest sounding known between Acheen and the 

 Nicobars, since the temperature at 1200 fathoms east of the ridge is that appropriate 

 to 740 fathoms to the west of it. Since then the indication of 736 fathoms as the 

 depth on the line from the Nicobars to the Andamans is a striking confirmation of 

 the justice of Carpenter's reasoning. 



