200 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
from the outcrops I saw just above its base, but from all the other 
mountains of the central igneous region. 
I endeavored to ascertain the geologic structure of Cerro Angon, but 
owing to the dense vegetation and residual soil no exposures of bed rock 
could be found, except at the Canal Company's hospital on the north side 
and along the water front upon the south. At both localities outcrops 
extend to about 100 feet above the base of the mountain. Тһе only 
rocks exposed were highly disturbed stratified material of greenish white 
color which is later described as the Panama formation. Neither Maack 
nor other explorers have succeeded in ascertaining the material compos- 
ing the higher slopes of the mountain. 
The Panama Formation. — A formation analogous to the beds at 
Miraflores occurs along the Pacific coast in the city of Panama and in 
the adjacent islands. At Panama it constitutes the steep bluff at the 
water front, as well as the strip of land extending eastward toward the 
mouth of the canal at the foot of Cerro Angon. This same rock also 
outerops upon the island of Naos, four miles out in Panama Bay. 
The geologic composition of the material at Panama is a greenish 
white stratified fine grained material resembling sandstone with occa- 
sional beds of conglomerate. These beds are quite strongly flexed, 
similarly to those at Miraflores, indicating that they have undergone 
considerable disturbance since their original deposition. No traces of 
fossils could be found, nor other evidence affording the least indication 
of the age of this material, or its relation to the other sedimentaries. 
Maack! has described the material of the Panama formation, and Mr. 
Garella? also noted it. 
The specimens collected by the writer from this peculiar formation 
were submitted to both Professor Wolff and Mr. Turner for determina- 
tion. Mr. Turner says concerning 16 : — 
“Тһе specimen Мо. 45, from the Panama Cemetery Gate, is of volcanic 
origin. Тһе rock has a micro-erystalline feldspathie groundmass in which are 
embedded abundant broken feldspars, with a few showing idiomorphic out- 
lines. Many of the feldspars are twinned on the albite law, and as their index 
of refraction is less than that of the balsam, these twinned feldspars are albite. 
No original meta-silicates were seen, but there are patehes and spots of a green 
secondary pleochroic substance, probably in part chlorite, in one patch of which 
1 Ор. cit., page 164. 
2 Project of a Canal to connect the Atlantic and Pacific Oceans across the 
Isthmus of Panama, by Napoleon Garella, Engineer in Chief of the Royal Corps of 
Miners. Rep. No. 145, U. S. House Rep., February 20, 1849, page 520. 
