314 MEMOIRS OF THE CARNEGIE MUSEUM. 



31. Pygidium unicolor Regan. 

 Pygidium unicolor Regan, Ann. & Mag. Nat. Hist. (8), XII, Nov., 1913. (Con- 



doto.) 



Habitat. San Juan basin. 



The following is the original description of Regan: 



"Depth of body 7 in length, length of head 6. Head as broad as long. Diam- 

 eter of eye 12 in length of head or 3 in interocular width; eyes well in advance of 

 middle of head, close behind nostrils. Barbels as long as head. Dorsal 8-9, with 

 5 or 6 branched rays, rounded; origin above or a little in advance of vent, 1^ as far 

 from end of snout as from base of caudal. Anal 7, with 4 branched rays; origin 

 below last rays of dorsal. Pectoral filament i to as long as head, branched rays # 

 length of head. Pelvics covering vent. Caudal subtruncate. Coloration uni- 

 form. 



"Two specimens, 80 and 85 mm. in total length, from the Condoto (Spurreh 1 )." 



32. Pygidium kneri (Steindachner). (Plate XLVI, figs. 1, 2.) 

 Trichomycterus knerii Steindachner, Ichthyol. Beitr., XII, 1882, p. 21, pi. V, 



figs. 1-la. 



Habitat. — Canelos, Rio Bobonaza; Rio Zamora, eastern slope of Ecuador; 

 Rio Meta, eastern Colombia. 

 13907, I. U. M., one, 155 mm. Barrigona, Rio Meta. Gonzales. 



Head 5.7; depth 6.3; D. 10; A. 10 including the rudimentary rays; eye 9 in the 

 head, interocular 3, snout 2.3; eye in middle of the head. 



Nasal barbel extending a little beyond gill-opening, as long as the head; maxil- 

 lary barbel reaching to near tip of the shortest pectoral ray; first pectoral ray with 

 its filament a little longer than the head, the rays about equal to the part of the 

 head behind the nasal barbels; origin of ventrals equidistant from base of middle 

 caudal rays and the eye; origin of anal under last dorsal ray; caudal truncate when 

 half expanded, slightly rounded or emarginate when fully expanded or compressed, 

 its middle rays equal to the length of the head; dorsal rays coterminous when de- 

 pressed; distance of origin of dorsal from base of middle caudal rays 1.6 in its dis- 

 tance from the snout; depth of caudal peduncle about 1.5 in its length, which is 

 five in the length. 



Slightly darker above, without spots or streaks. 



Steindachner's description and figure give the following variation from the 

 above. 



"Head 5.25-5.66; depth 6.75-7.5; D. 9; A. 7; eye 5-6 in the head; snout 2.5; 

 interocular 2.66-3.75; width of the head 1.33-1.4 in its length. 



