eigenmann: the pygidiid^e, a family of south American catfishes. 281 



filament; opcrcle with a long dermal flap; interopercular spines in a much more 

 restricted area than in species of Pygidium; accessory rays of the caudal inconspi- 

 cuous; maxillary barbel with a large osseous base (maxillary). Teeth very narrow 

 incisors; mouth wide, terminal. 



In other respects like Pygidium. 



Habitat that of the single species. 



1. Scleronema operculatum Eigenmann. (Plate XLIV, fig. 1.) 



Scleronema operculatum Eigenmann, Proc. Am. Philos. Soc, LVI, Jan., 1918, p. 691. 

 7077, C. M., type, one, 79 mm.; 7539 a-c, C. M. paratypes, 65-80 mm. Cacequy, 



Uruguay basin. Feb. 1, 1909. Haseman. 



Head 5.2-5.66; D. 12.5; A. 7.5 counting the rudimentary rays; P. 7; eye in 

 anterior half of the head; interocular five times in the length of the head; width of 

 mouth nearly half the length of the head. 



Nasal barbel short, reaching just beyond posterior nares; maxillary barbel 

 reaching about half-way to the tips of the opercular spines, the bony base much 

 longer than the soft filament; a broad, free membrane above from near the anterior 

 nares to the tip of the osseous base of the barbel, a narrower membrane along the 

 outer edge of the base of the barbel ; six spines in the main row of the interopercle ; 

 opercular flap reaching to or beyond base of the last pectoral ray; pectoral about as 

 long as the head; origin of ventrals about equidistant from the snout and from the 

 base of the middle caudal rays: ventrals reaching beyond the anus, not quite to the 

 anal, equal to the portion of the head behind the nasal barbels; origin of anal under 

 the posterior part of the dorsal, the distance from the base of its last ray to the 

 caudal four times in the length; caudal narrow and long, equal to the length of the 

 head, its margin slightly oblique, rounded; origin of dorsal over posterior half of 

 ventrals, the distance from the first ray to the caudal 1.3 in its distance from the 

 snout. 



Middle of sides with a series of large spots, similar spots along the back. 



Genus III. Hatcheria 15 Eigenmann. (Plate XXXVI.) 



Hatcheria Eigenmann, Reports Princeton Univ. Exped. Patagonia, III, 1909, p. 248. 



Type. — Hatcheria patagon iensis Eigenmann. 



Origin of dorsal behind that of the ventral, which is near middle of the body; 

 nasal barbels large; two barbels of nearly equal size at the angle of the mouth; no 

 mental barbels; mouth terminal; teeth conic or narrow incisors, in a few -series; 

 15 In memory of J. B. Hatcher, leader of the Princeton University Expeditions to Patagonia. 



