858 Twin Lakes and Teocalli Mountain, Central Colorado, {Dec., 
true Felis by the round form of its pupils. This can only be ob- 
servéd in the living species, so that some correlated index of it 
must be used in determining the genus from skulls. This Dr. 
Gray shows is seen in the small size of the orbits, which are 
always less than those of the species of Felts. 
Fragmentary remains from the Loup Fork formation of Ne- 
braska and the Piiocene and Quaternary of Mississippi and Cali- 
fornia have been described by Leidy under the names of Fels 
augustus, F. atrox and F. imperialis. Dr. Leidy suggests that 
there may have been two species, the one (F. augustus) charac- 
teristic of the Loup Fork epoch, and F. atrox, the second, belong- 
ing to a later period. The Uncia augusta was intermediate in 
_ size between the U. onca and the tiger, while the Uncia atrox was, 
according to Leidy, larger than the lion or tiger. It represents 
in America the Uncia spelea of the European caves, and should 
be carefully compared with that species. 
sangre LÈ eg cents 
TWIN LAKES AND TEOCALLI MOUNTAIN, CEN- 
TRAL COLORADO, WITH REMARKS ON THE 
GLACIAL PHENOMENA OF THAT REGION. 
BY F. V. HAYDEN, 
NE of the most interesting localitie# in Central Colorado, is 
the Twin lakes. These lakes are situated at the point where 
Lake Fork issues from the Sierra Madre, or Wasatch range, into 
the short valley which opens into the Upper Arkansas. At no 
distant period this point, with its surroundings, will form one of 
the most popular and desirable watering places in the West; 
already every available spot in the vicinity has been purchased for 
the purpose of erecting summer houses. The elevation of the 
lakes is 9357 feet above sea level. Some of the loftiest peaks T 
Colorado are in full view of the surrounding hills. Massive 
mountain, Mt. Elbert, Harvard, Yale and Princeton peaks, rise to 
heights of over 14,000 feet. The massive granite mountains on 
every side, are among the most rugged and picturesque 1n me 
Rocky Mountain region. : 
During the survey of this region in 1873, under the direction 
of the writer, these lakes were carefully sounded, and me 
greatest depths were found to be respectively seventy and 
seventy-six feet, These are formed in basins, as it were, which 
