PIMELODUS. 137 
5. PIMELODUS, Lacep., 1803. 
Pimelodella and Pimelodus, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, pp. 153 & 154. 
Occipital process extending to shield at base of dorsal spine ; dorsal spine pungent ; in other respects similar 
to Rhamdia. 
Numerous species, ranging from Panama to La Plata. 
Synopsis of the Mexican and Central-American Species. 
I, Head covered with smooth skin; maxillary barbel about reaching origin of adipose fin. 
Occipital process twice as long as broad ; adipose fin about # the length of the 
fish... ww ke kk kk ee ek kk kk 1. chagresi. 
Occipital process 3 times as long as broad; adipose fin } the length of the fish . . 2. modestus. 
II. Head naked, rugose; maxillary barbel extending to caudal fin . . . . . 3. maculatus. 
1. Pimelodus chagresi. 
Pimelodus chagresi, Steind. Sitzungsb. Ak. Wien, lxii. 1876, p. 584". 
Hab. Panama, Rio Chagres. 
2. Pimelodus modestus. 
Pimelodus modestus, Giinth. Proc. Zool. Soc. 1860, p. 239', and Cat. Fish. v. p. 117 (1864) *. 
Hab. tPANAMA.—WESTERN Ecuapor !°, 
P. modestus has been recorded from the Rio Chagres by Kner and Steindachner 
(Abhand]. Bayer. Ak. x. 1865, p. 49), but it is not improbable that this record 
refers to the preceding species, which appears to differ from it only in the characters 
given in the key. 
3. Pimelodus maculatus. 
Pimelodus clarias, Steind. Denkschr. Ak. Wien, xli. 1879, p. 162°. 
Pimelodus maculatus, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 155°. 
Hab. Panama, Rio Mamoni!, 
Steindachner’s description of specimens from the Rio Mamoni, Panama, is not 
sufficiently detailed to show whether they should be referred to one of the South- 
American species which have been placed together under the names P. clarias, L., 
or P. maculatus, Lacep. The specimens in the British Museum which come nearest 
to them geographically are from Colombia, but these are certainly distinct from the 
Mamoni River form. ° 
BIOL. CENTR.-AMER., Pisces, November 1907. T 
