March, 1914. List or Fishes of 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 Siluridae. 



Rhamdia rogersi (Regan). 



Pimelodus rogersi Regan, Ann. & Mag. Nat. Hist., 1907, 259 (Irazu, 

 Costa Rica). 



Rhamdia regani Meek, Pub. Field Mus., Zool. Ser., vii, 1907, 144 

 (Turrialba and Rio Tiribi, San Jose, Costa Rica). 



Rhamdia hrachyce phala Meek (not Giinther?), Pub. Field Mus., 

 Zool. Ser., vii, 1907, 144 (Turrialba, Costa Rica). 



Rhamdia rogersi Regan, Biol. Cent. Amer., 1907, pi. 23, fig. i, 136. 



This species is very abundant in the streams about San Jose, 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 Jose market. In the San Jose 

 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 to rather robust. It is 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 Giinther, and 

 may prove to be identical with it. 



Turrialba (17), 75 to 175 mm. (Alfaro); El Guayabo (8), 78 to 180 

 mm. (Alfaro); Chitaria (i), 135 mm. (Alfaro); Rio Tiribi (3), 114 



