224 Fre~tp Museum or Natura History — Zoétrocy, Vor. X. 
That the faunas of these small streams are of much interest is indicated 
by the fact that Hoplosternum punctatum sp. nov. belonging to a dis- 
tinctly South American family, of which heretofore no representative 
was known north of the Rio Atrato Basin in Colombia, was taken in 
the Rio Marte Arnade, a small stream, about 6 miles east of Panama 
City, and was not seen elsewhere in Panama. Gephyrocharax inter- 
medius sp. nov. was found only in the Rio Chame; Bryconamericus 
cascajalensis sp. nov. only in the Rio Cascajal at Porto Bello; Rivulus 
brunneus Meek & Hildebrand only in a small coastal stream at Toro 
‘Point and Microeleotris panamensis gen. et sp. nov. only in the Rio 
Juan Diaz and the Rio Chorrera. Ancistrus chagresi, which is com- 
mon in the Rio Chagres Basin, was taken on the Pacific slope only 
in the Rio Chorrera. 
Tue Rio CHAGRES AND Its FAUNA. 
The Rio Chagres is but slightly affected by tides at its mouth, as 
there is a difference of less than two feet between mean high and mean 
low water on the Atlantic coast of Panama. Ascending this stream, it 
is found to flow through a low swampy region in its lower course, or as 
far as Gatun. Here it receives its largest tributary, the Rio Trinidad, 
which is a sluggish stream winding its way for many miles southward 
through a low, dense jungle where mosquitoes abound in countless 
numbers. It reaches the mountains opposite the Rio Chorrera. In 
the upland regions it is free from rapids, but the current is swift. 
At Gatun the Rio Chagres receives another tributary of considerable 
size, namely, the Rio Gatun, which assumes an easterly course, and is a 
clean, clear stream, usually with sandy or pebbly bottom and without 
rapids or falls but with a strong current. 
Following again the course of the Rio Chagres from Gatun upward 
it assumes the general direction of the present Canal, i. e., southeast- 
ward until Gamboa is reached where it makes a rather sharp turn to the 
left and then follows an east by northeast course. As far up as Alha- 
juela or about 50 miles from its mouth, following the winding course of 
the stream, the current is swift but no rapids occur. From this point 
upward it becomes swifter and at intervals rapids appear which can 
be crossed only when the water is at a low stage. At San Juan, the 
last native village on the river, the stream forks; the left fork is known 
as the Rio Pequeni which soon again divides forming the Rio Boqueron 
and the Rio Pequeni. The fork to the right, going up stream, at the 
village of San Juan is the Upper Chagres. Following its course the 
mouth of a large tributary is soon reached. This is the Rio Indio which 
has a waterfall a short distance above its mouth; below it a large num- 
