Marcu, 1914. List or Fisnes or Costa Rica — MEEK. 103 
Atlantic. It was impossible to use a seine in the main channel of the 
Rio TArcoles and so our collecting was confined to small bayous and 
cutoffs along the main stream. The Rio Machuca is a swift stream 
with many rocks and occasionally level stretches. Rio Turrubales 
has a moderately swift current and a sandy and gravelly bottom. 
Much the same conditions exist in the Rio Jesus Maria, only the cur- 
rent is less swift. 
Family Siluride. 
Rhamdia rogersi (Regan). 
Pimelodus rogersi Regan, Ann. & Mag. Nat. Hist., 1907, 259 (Iraza, 
Costa Rica). 
Rhamdia regani Meek, Pub. Field Mus., Zoél. Ser., vit, 1907, 144 
(Turrialba and Rio Tiribi, San José, Costa Rica). 
Rhamdia brachycephala Meek (not Ginther?), Pub. Field Mus., 
Zool. Ser., vii, 1907, 144 (Turrialba, Costa Rica). 
Rhamdia rogerst Regan, Biol. Cent. Amer., 1907, pl. 23, fig. 1, 136. 
This species is very abundant in the streams about San José, and 
appears rather common in the upland streams tributary to the Reven- 
tezon. It remains hidden under stones, and in other hiding places 
during dry weather. After a few rains in the latter part of April and 
in May they come out in large numbers in grassy places, where they 
are easily caught, and sold in the San José market. In the San José 
valley this is the only fish which grows large enough to be regarded 
as a food fish. 
The species varies somewhat. Some of the larger ones are more 
slender than the others, and the occipital process may be long and 
narrow torather robust. Itis very probable that the species of Rhamdia 
in Central America have been unduly multiplied. This is due to the 
fact that they are subject to more variation than has been suspected 
and to the difficulty in securing sufficient material to study these varia- 
tions. I have spent many hours in attempting to get these fishes from 
their hiding places in streams where I had reason to believe they were 
plentiful, with little or no results. I have never collected in the tropics 
in the rainy season when they are said to be abundant in shallow water. 
This species is very much like Rhamdia brachycephala Ginther, and 
may prove to be identical with it. 
Turrialba (17), 75 to 175 mm. (Alfaro); El Guayabo (8), 78 to 180 
mm. (Alfaro); Chitaria (1), 135 mm. (Alfaro); Rio Tiribi (3), 114 
