226 Frecp Museum or Natura History— Zoéxoey, Vor. X. 
1911, it rose from an elevation of 101.4 feet at 9:00 A. M. to 110 feet by 
10:00A.M. Itis evident that at such times all boating on the river must 
cease. 
The fish fauna in the upper courses of the Chagres is rather rich in 
quantity but rather poor in variety. On the lower courses of the 
Chagres the larger fishes have become comparatively rare, owing in 
part at least to the illegal use of dynamite, but the number of species is 
greater than in the uninhabited region. 
The following is a list of species obtained by us in the Rio Chagres 
Basin: Family Siluride; Pimelodella chagresi, Rhamdia wagneri: Family 
Loricariide; Plecostomus plecostomus, Chetostomus fischeri, Ancistrus 
chagresi, Loricaria uracantha: Family Characide; Astyanax ruberrimus, 
Bryconamericus emperador, Brycon petrosus, Brycon chagrensis, Gephyro- 
charax atricaudata, Creagrutus notropoides, Hyphessobrycon panamensts, 
Pseudocheirodon affinis gen. et sp. nov., Compsura gorgone, Reboides 
guatemalensis, Piabucina panamensis, Hoplias microlepis: Family 
Gymnotide; Hypopomus brevirostris: Family Paeciliide; Gambusia 
cascajalensis, Gambusia episcopi, Gambusia nicaraguensis, Mollienisia 
sphenops, Priapichthys tridentiger, Rivulus elegans: Family Mugilide; 
Agonostomus macracanthus, Agonostomus monticola, Joturus pichardi: 
Family Cichlide; Aiquidens ceruleopunctatus, Cichlasoma maculicauda, 
Neetropolus panamensis, Geophagus crassilabris: Family Gobiide; 
Awaous taiasica, Dormitator maculatus, Leptophilypnus fluviatilis gen. 
et. sp. nov., Microeleotris mindii gen. et sp. nov., Eleotris isthmensis 
sp. nov., Eleotris pisonis, Guavina guavina, Philypnus dormitor, and 
Sicydium salvini. 
The representatives of the family Siluride occur on both slopes of 
Panama and southward and seem to be well established species that are 
not at the present time undergoing any rapid changes in different 
localities. 
Of the family Loricariide, Loricaria uracantha was taken only in the 
Rio Chagres* and does in fact have no very near relatives. Since the 
Isthmus of Panama is the northernmost limit of the range of this family 
and its center of distribution occurs somewhere in South America, this 
species may be regarded as one of the earliest migrants,t which appears 
to have changed remarkably under the new environment. Chetostomus 
fischeri is really a Pacific slope fish in Panama, but it seems to have 
reached this region before the last gap between the Rio Chagres and 
the Pacific slope streams was closed. It has apparently not thrived 
*Loricaria uracantha is recorded from the Pacific slope of Panama, but it was 
not seen there by us. 
tIn our discussion on distribution, Panama is regarded as a very remote center: 
of distribution. See Meek, Field Mus. Nat. Hist. Pub., Zodl. Ser., X, 1914, p. 134. 
