218 Wisconsin Academy of Sciences, Arts, and Letters. 
With a 30 cm. disc, Meek found a transparency of about 3.5 m. 
The water is slightly brackish, the total solids amounting to 421 
parts per million. Of this amount, sodium and potassium chlor¬ 
ide constitute 210 parts per million. The other important con¬ 
stituents are as follows: Silica, 40 parts per million; iron and 
alumina, 6; calcium, 56; and magnesium, 7.8. 
The larger aquatic plants, such as Typha, Scirpm, Potamoge- 
tpn, Ceratophyllum, and Chara, are fairly abundant in the shal¬ 
low water along the shores, but they grow most luxuriantly along 
the lowland on the north side of the lake. A floating plant, Sal - 
vinia natans, is widely distributed also, but it is most abundant 
in the vicinity of hot springs. Another floating plant, the 
water-lettuce or Pistia obcordata is found in the lake, but it is 
confined mainly to the low shore on the north side. 
LAKE ATITLAN. 
Atitlan is a mountain lake situated on the Pacific slope of 
Guatemala, about due west of Guatemala city. It is about 40 
km. from the nearest railway station, viz., that of the village of 
Patulul. The lake lies at an altitude of about 1500 m. above sea 
level and is said to have an excellent climate during the entire 
year, being free from excessive heat in summer as well as un¬ 
usually cool weather in winter. Coffee and tropical fruits, such 
as lemons, oranges, and bananas, are grown in abundance in 
this vicinity. With the exception of a small portion of the 
southern shore, the lake is bordered by mountains which rise 
to a general altitude of 750 m. or more above its surface. In 
many places the shores rise perpendicularly from the water’s 
odge to a height of 50 m. or more. 
Several craters of extinct volcanoes are found on the south 
side of the lake and give mute evidence of the volcanic activities 
that once took place in this region. The most prominent cones 
are Atitlan and San Pedro. The former rises about 2100 m. 
above the surface of the lake, and the latter about 1500 m. 
The lake is fairly regular in outline with a prominent bay ex¬ 
tending southward. (See sketch map, fig. 2, p. 219.) The 
maximum length is about 38 km. and the longest axis lies in a 
northeast-southwest direction. The maximum width is about 
half the length, but the mean width is not more than a third of 
the length. It seems probable that the basin occupied by the 
