i68 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. VII. 



Guatemala. From these analyses, the following table was prepared 

 by Mr. Nichols, of this Museum: 



Parts per million. 

 L. Michigan. L. Amatitlan. 



Silica 5 .00 40 .00 



Calcium Carbonate 50 .00 140 .00 



Magnesium Carbonate 16 .68 27 .30 



Calcium Sulphate 22.77 trace 



Sod. & Pot. Chloride r 4-75 210.00 



Sod. & Pot. Carbonates . 2.24 .... 



Ferric Oxide & Alumina trace 6 . oo 



Phosphates trace 



Potassium Nitrate 2 .00 



Nitrates none 



Ammonia .02 



Oxygen consumed 



in acid sol 4.6 



in alkaline sol 4.6 



Total solids 1 1 1 . 40 42 1 . oo 



It will be noticed that the total solids in the water of Lake Ama-- 

 titlan is nearly four times that of Lake Michigan, although but about 

 i . 2 per cent of that of sea water. The water of Lake Amatitlan, 

 though considerably used by the residents for drinking purposes, is 

 not a good potable water. It is slightly salty to the taste, and its 

 oxygen consuming power indicates the presence of considerable de- 

 composing organic matter, and consequently the probable presence of 

 bacteria. It is probable that this test of the water was made some 

 time after the water was taken from the lake, and is not a fair indica- 

 tion of its actual condition. By the residents of this region the lake 

 water is regarded as poor for drinking purposes. 



The amount of mineral matter in the lake is too small to unfit the 

 water for fresh water fish life. The volume of water is large, and the 

 inflow and the outflow great enough to prevent the lake water from 

 ever becoming salty to any harmful extent. 



The shore vegetation of the lake may be characterized as only 

 moderately abundant. A few large trees, as the Willow (Salix 

 Humboldtiana), and several species belonging to the genus Ficus 

 (Rubber-trees) grow close to the water's edge, their low, drooping 

 branches being often bathed by the waves. These trees afford a con- 

 siderable amount of shade, which appears to be a favored hiding place 

 for fishes in the lake. This, and other land vegetation, supports a 

 large number of Fungi and Epiphytes (Orchids and Bromeliads) attrac- 

 tive to insects, which are constantly falling into the lake and forming a 

 supply of food for fishes. There are no extensive forest areas on the 



