OF ARTS AND SCIENCES. 285 



Bay and the southern shores of the lower lake. The myriophyllum 

 ^rows very hixuriantly, anil forms an important article of food for the 

 cattle of the lake shore. It is not an uncommon sii^ht to see tho 

 cows of Puno wading up to their middle in the water, and diving 

 boldly in search of their food which they cannot find on the shore. 

 This habit has as yet produced no apparent effect on these amphibious 

 cows, although carried on for a good many generations. The fields of 

 Totora are also the feeding places of the myriads of aquatic birds 

 which abound along the lake shore, and which are the most charac- 

 teristic feature of the Fauna of the lake. The fishes and reptiles are 

 not numerous,* and our collections of the former showed a poverty in 

 S2>ecies which is most remarkable, and this is also accompanied by a 

 comparative jioverty in the number of sjiecimens, except in certain 

 localities. The scarcity of fishes can, however, be readily explained 

 when we examine the physical condition of the water, which is cer- 

 tainly not well adapted to them. In the first place, the whole bottom 

 of the lake, as I have mentioned before, is covered with silt, thus ren- 

 dering unfit a large part of the area of the lake for the fishes and rep- 

 tiles, leaving only the shallower bays, a more or less wide belt along 

 the shore according to the nature of the adjoining country, and the 

 lower lake, which appears to be the favorite fishing post of the Indians. 

 This, however, may be due to the greater energy of the Bolivian In- 

 dians, who are a finer set of men, more willing to work, and in every 

 way superior to the lazy natives found near Puno and the northern end 

 of the lake. In the second place, the temperature of the water of the 

 lake is so high that none of the fishes which abound in the lakes of 

 our temperate zone are to be found. There are in all only six species 

 of fishes, Cyprinoids and Siluroids, — a remarkably small number for 

 a sheet of water as large as Lake Erie. They were all known before. 

 In the way of reptiles, the most interesting species was a huge frog, 

 which remained often for hours perfectly quiet on the bottom, sus- 

 pended on fronds of myriophyllum, apparently too lazy to come up 

 to the surface to breathe. 



The effect of the vertical sun upon the temperature of the water is 

 very marked, extending to its deepest point, and heating the whole 

 body of water to such an extent that the greatest difference we ob- 

 served was in one case, it is true, as high as 6J degrees at a depth 

 of 103 fathoms; but the usual difference between the surface and 



* See Bull M. C. L. Vol. III. No. 11. 



