318 PROCEEiDINGS OF THE NATIONAL MUSEUM vol.94 



of the Rio San Ignacio, 25 km. south of Rosario, Maracaibo Basin, 

 on February 26, 1942; U.S.N.M. No. 121013, 2 specimens, 85.7 and 

 210 mm., from a cafio, half a mile west of Sinamaica, Alaracaibo 

 Basin, March 11, 1942. 



The holotype and paratypes when captured were all living on muddy 

 bottoms and in shallow water. 



Description. — Based on the holotype and three paratypes. De- 

 tailed measurements and counts are presented in table 21. 



Bony ramus of upper and lower jaws about equal in length, the 

 teeth bifid, the inner lobe much the largest, teeth numbering about 

 27 to 32 above and 26 to 31 below; barbel at corner of mouth l^ 

 to 2}^ in the interorbital space; supraoccipital with a rounded keel 

 in the middorsal line posteriorly and bounded posteriorly by a single 

 median plate in the adult, but in the small specimen this plate has not 

 yet fused in the middorsal line to form a single plate; the next dorsal 

 plate is double, but the first plate m front of the dorsal fin origin is a 

 single plate with expanded wings; interorbital space convex, rims of 

 orbits dorsally a Httle elevated, especially so in the young; snout with 

 prickles to its tip and no naked area present; breast and belly with 

 platelets, rough in the young; the interopercle is movable, but the 

 spine on it is not concealed by the opercle; interopercle and opercle 

 not so freely movable as in other related genera ; most of the plates of 

 the body are keeled, especially in the young, these plates becoming 

 smoother with age; body robust, its greatest depth at origm of dorsal, 

 3.8 to 4.0 in the standard length, width of body at coracoids 3.0 to 

 3.4 and head 2.9 to 3.3; ramus of lower jaw 3.0 to 3.6 in interorbital 

 space; eye 4.0 to 6.9, in snout, and 7 to 12 times in the head; the least 

 depth of the caudal peduncle is contained 2.4 to 3.3 in its length; 

 the pectoral spine, very spiny in the adults, reaches past middle of the 

 pelvic spine; the depressed dorsal fin on the adult docs not quite reach 

 the origin of the dorsal, fallmg short by one plate, but in the yomig it 

 reaches to opposite the base of the caudal fin; the caudal fin with outer 

 upper and lower rays exserted is less deeply forked in the large speci- 

 mens; the depressed anal fin reaches to opposite the middle of the 

 adipose; in the small specimen a keel extends backward from upper 

 part of eye, but in the adult the ridges on the head are obsolete; 

 the interopercle has one spine, hooked at its tip, and several very 

 short small points or spines around it, but on the young the hooked 

 spine is undeveloped. 



Color. — Ground color of body brownish to blackish, the upper parts 

 of head with very numerous small black spots, larger in the young; 

 sides of body anteriorly with numerous larger black spots, these 

 absent on the caudal peduncle; but present on the belly and under- 

 sides of the head; in the young the spots are much larger and less 



