370 Field Museum of Natural History — ZoOlogy, Vol. X. 



Head 4.17 to 4.85; depth 4.85 to 5.75; D. VI-I, 10; A. I, 10; scales 

 70 to 86. 



Body elongate, anteriorly subcylindrical, posteriorly compressed; 

 head short, quadrate, as wide as deep; snout very short and blunt, 

 anterior profile nearly vertical, its length 2.2 to 2.96 in head; eye small, 

 lateral, placed high, 4.7 to 5.75; interorbital 3 to 4.3; mouth large, hori- 

 zontal, inferior; the upper jaw notably in advance of the lower, the lip 

 thickened; maxillary reaching to or past posterior margin of eye, 1.7 to 

 2.2 in head; teeth in upper jaw in a single series, very slender, recurved, 

 somewhat compressed and grooved at apices, tricuspid in young, with 

 nearly smooth cutting edge in adult; lower jaw with 2 series of teeth, 

 the outer series nearly horizontal, directed forward, more or less exposed 

 in young, but completely hidden in the gums in adult; second series 

 composed of comparatively few, rather strong, vertical or slightly re- 

 curved, pointed teeth; gill-openings vertical, not extending forward; 

 scales small mostly ctenoid, extending forward nearly to interorbital 

 region; abdomen completely covered with scales; those on predorsal 

 region and abdomen very small and partly embedded; origin of first 

 dorsal about midway between posterior margin of eye and origin of 

 second dorsal, the spines produced in adult males, sometimes reaching 

 past middle of base of second dorsal; origin of second dorsal midway 

 between posterior margin of eye and base of caudal or slightly nearer the 

 latter, notably higher in adult males than in females; caudal fin scaly at 

 base, the margin rounded; anal fin similar to second dorsal, but scarcely 

 as high; ventral fins forming almost a perfect circular disc; pectoral 

 fins broad at base, rounded, 1.05 to 1.4 in head. 



Color dark green. Young with a dark lateral band, which later 

 breaks up into more or less confluent spots; sides also with dark cross- 

 bars, which are very indistinct in our largest specimens; back in young 

 with dark reticulations; scales usually with roundish spots which are 

 largest and most distinct on caudal peduncle. Dorsal fins spotted or 

 not; anal fin with a dark stripe near its margin. 



We have 8 specimens of this species, ranging from 55 to 100 mm. in 

 length. One of these was taken at Paraiso, on the Pacific slope, in a 

 small tributary of the Rio Grande, and the others are from various places 

 in the Chagres Basin. We are unable to separate the Pacific slope 

 specimen from those of the Rio Chagres. Our specimens were all taken 

 in upland streams where the species inhabits the rocky rapids. By 

 means of its ventral sucking disc, it is able to cling closely to the rocks 

 and is extremely difficult to capture. It is therefore quite certainly not 

 as rare as the small number captures would indicate. 



Habitat : Both slopes of Panama and Western Ecuador. 



