30 ILLINOIS ACADEMY OF SCIENCE 



tures may be quite high. But nights are always cold, and 

 the passing of a cloud over the face of the sun will cause 

 the fisherman to assume his coat. In equal altitude at 

 Cebollar, Chile, a diurnal temperature variation of 65° F. 

 was encountered. 



While the elevation is too great to allow more than a 

 few land plants, there is still an abundance of aquatic 

 vegetation. The lake bottom is deeply covered with mud 

 and flocculent organic debris. Ceratophyllum, Potamo- 

 geton, and Philotria are abundant. The exposed roots 

 of the shore plants at the water's edge are covered with 

 great quantities of green fresh-water sponge, of which 

 adequate collections were made. 



The fish are of only two species, but very numerous in 

 individuals. They are: the hagre, a Pygidium, catfish, 

 which the inhabitants say ascends the rivers to spawn; 

 and the challhua, an Orestias. 



The fish are only slightly susceptible to dynamiting. It 

 affected only those nearest the explosion. Most of these 

 instead of rising to the surface as w^as expected sank 

 into the ooze at the bottom and w^e lost. At first one 

 is inclined to attribute this to the great elevation, and the 

 decrease of about two-fifths of the atmospheric pressure. 

 But the fishes here are apparently in as perfect adjust- 

 ment to the existing hydrostatic pressure as at any other 

 elevation, and ought therefore to respond in a similar 

 way. It was disconcerting to cruise (in a motor launch 

 kindly loaned by an American gun club at La Fundicion) 

 among the reedy embayments and lagoons, seeing vast 

 numbers of fish in the clear w^ater, unable to interest them 

 in hook and line, unable to manipulate a seine, or to 

 dynamite successfully, and the fish always out of reach 

 of a dip net. The Peruvian came to the rescue. With 

 a hardihood inherent in the dwellers of the bleak pampas 

 he stepped into the water to his thighs, supporting his 

 weight upon the rhizomes and roots of plants. Here he 

 searched among stems for the fishes lurking there, and 

 found them. 



Very large frogs, Cyclorhamphus culeus Garman, were 

 found fairly abundant in the lake and its tributaries. 



