286 The American Naturalist. [March, 
ARCHAOLOGY AND ETHNOLOGY. 
Prehistoric Occupation in Cambodia.—Shell-heaps in 
Asia.—Polished Stone Implements in the National Museum. 
—The principal river of Cambodia is the Me-Kong. Its source is far 
up in the mountains of Thibet, where it has the name of Lam-Thsang- 
Kiang. It traverses the Chinese province of Yum-Nan, and those ot 
Laos and Cambodia, and enters the China Sea in the French province 
of the latter name, in latitude 10 degrees north, longitude 106 degrees 
and 40 minutes east. Its average width through Cambodia is 3,500 to 
4,000 feet. In its lower portion it divides itself many times and forms 
a network of navigable waters, and finally discharges itself through 
eight mouths. 
The present capital of the province is Phnom-Penh, situated on the 
Me-Kong, about one hundred and seventy-five miles from its mouth. | 
At the city of Phnom-Penh the river Me-Kong forks. It is the 
western fork with which this account deals. The eastern branch is the 
main river; the western branch is but a blind stream which, after the 
fashion of a bayou, is fed from the main river. Its length is one 
hundred and seventy-five miles, and it ends in an immense lake eighty 
or ninety miles in length called Ton-le-Sap. 
Each year the Me-Kong river, by reason of the melting of the snows 
in the mountains of the central plateaux of Thibet, overflows and 
inundates the lower country which it traverses. The level of the lake 
Ton-le-Sap is about thirty-six feet lower than that of the Me-Kong 
river at Phnom-Penh where the bayou joins the river. The period of 
inundation is the months of July, August and September, and at their 
beginning the waters from the river fill the bayou, run northward 
through its length, and empty in and fill the lake. During the inun- 
dation the water in the lake attains a depth of thirty-five or forty feet, 
and, consequently, spreads over a vast extent of the country which 
fore was uncovered. -On the termination of the flood and the sub- 
sidence of the water in the river, the current in the bayou is reversed ; 
it runs south, empties into the river, and so drains the lake. During 
the dry period, which lasts six months of the year, Ton-le-Sap, instead 
of being a great lake of water, is a plain of soft mud. 
The action of the water in this river and lake is similar to that of 
the Nile and the lake Moeris in Egypt. It is easy, with the illustration 
of the Nile, to understand the operation, and also the quantity of 
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