248 Field Museum or Natural History — Zoology, Vol. X. 



Plecostomus brasiliensis Bleeker, "Silnres de Suriname," 1864, 7 



(Surinam). 

 Plecostomus plecostomus Eigenmaim & Eigenmann, Proc. Cal. Ac. Sci., 



2nd Ser., I, 1888, 169. 

 Plecostomus seminudus Eigenmann & Eigenmann, Proc. Cal. Ac. Sci., 



2nd Ser., I, 1888, 169 (Brazil). 

 Plecostomus houlengeri Eigenmann & Kennedy, Proc. Ac. Nat. Sci. 



Phila., 1903, 502 (Paraguay). 



Head 3 to 3.44; depth 4.4 to 5.3; D. I, 7; A. I, 4; lateral scutes 25 to 

 28. 



Body anteriorly depressed, wider than deep; caudal peduncle poste- 

 riorly compressed; dorsal profile anteriorly convex; ventral surface 

 straight, flat; head low and wide; snout broad, its margin granulate 

 except a small triangular area at tip, 1.6 to 1.75 in head; eye 5.25 to 10; 

 interorbital 2.2 to 2.9; mouth wholly inferior; the lips broad, expanded, 

 forming a sucking disc; a single short barbel at angle of mouth; teeth 

 placed on the ramii of the jaws, slender, bifid, curved inward near tip; 

 the ramus of lower jaw 2 to 3.35 in interorbital; occipital and temporal 

 plates each with a median ridge, the former bordered posteriorly by 

 only a single scute; scutes on upper surface of body carinate, spinulose; 

 3 scutes in advance of dorsal; 6 or 7 between dorsal and adipose; 13 to 

 15 from anal to base of caudal; ventral surface in advance of vent 

 mostly covered with small granular scales; dorsal fin inserted in 

 advance of anal, nearer tip of snout than adipose fin, its base a Httle 

 shorter than head, its spine usually about length of head, 2.9 to 3.75 in 

 length; adipose fin well developed, situated somewhat nearer base of 

 caudal than base of last ray of dorsal; caudal fin emarginate, the lobes 

 produced, the lower one usually the longer; anal fin small, its origin a 

 little behind base of last ray of dorsal; ventral fins rather large, reaching 

 well past origin of anal; pectoral fins long, reaching far beyond base of 

 ventrals, the spine much enlarged in adults, bearing recurved spinules. 



Color above dark green; head and ventral surface with green spots, 

 these varying notably in size among individuals; fins usually bluish 

 green, with large spots of pale green, those on lower fins arranged so as 

 to form more or less distinct bars. 



This species is represented by 150 specimens, ranging in length from 

 40 to 400 mm. It was found fairly common on both slopes of Panama, 

 except in the Rio Bayano Basin where no specimens were obtained. 



This fish lives in rocky streams and is difficult to catch with a seine. 

 Most of our specimens were secured by the use of a set net, in which 

 they readily become entangled. 



Habitat: Both slopes of Panama, south to Uruguay. 



