EIGENMANN: THE PYGIDIID.E, A FAMILY OF SOUTH AMERICAN CATFISHES. 297 



(/. Uniform brown, darkest on the back; head flat above; width of head less than its length; 

 barbels scarcely extending beyond the eyes, which are in the middle of the head; a 

 broad band of villiform teeth in each jaw; first pectoral ray but slightly prolonged; 

 origin of dorsal equidistant from tip of caudal and nares, over posterior edge of base of 

 ventrals; last ray of the dorsal over the origin of the anal; caudal rounded, distance 

 between anal and caudal 4.5 in the length; ventrals nearer (ip of snout than to tip of 



caudal; head 5; depth 5. (ill; D. 10; A. 9 12. eigenmanni (Boulenger). 



(/</. Head and body with dark spots; a dark lateral stripe; head as broad as long; barbels 

 equal to eight-tenths the length of the head; snout slightly shorter than the postor- 

 bital part of the head; outer pectoral ray as long as the head, longest branched ray 

 three-quarters as long; origin of dorsal in advance of the vent, its distance from the 

 base of the caudal one and one-half times in its distance from the snout; origin of anal 

 slightly behind the last dorsal ray; caudal truncate; distance between anal and 

 caudal 4.5 in the length; head 6.25; D. with six, A. with four branched rays. 



13. vittatum (Regan). 

 cc . Caudal emarginate. 



r. Back and sides profusely spotted; head longer than broad; barbels not quite reaching gill- 

 openings; origin of ventrals equidistant between tip of snout and tip of caudal; 

 head 5.2-5.66; D. 12; A. 9 or 10. 

 /. Sides, back, dorsal, and caudal with large spots; spots as large as, or larger than, the 

 eye, smallest on the head; origin of dorsal equidistant from tip of caudal and 

 anterior margin of eye; distance between anal and caudal five or six times in the 



length 14. dispar Tschudi. 



//'. Spots much .smaller than the eye; origin of dorsal equidistant from tip of caudal and 

 a point between occiput and anterior margin of the eye; distance between anal 



and caudal 0-6.5 in the length 15. punctulatum (Cuvier & Valenciennes). 



ee. Back and sides unspotted; maxillary barbel reaching past origin of pectoral; origin of 

 dorsal varying with age; origin of ventrals a little nearer snout than to tip of caudal; 

 distance between anal and caudal five times in the length; head 4.66-5.5; eye minute, 

 in adult a little behind the middle of the head; teeth conic. 20 



16. taczanowskii (Steindachner). 

 66. Dorsal in part over the anal. 



g. Accessory caudal rays conspicuous; caudal rounded; outer row of teeth narrow incisors; 

 maxillary barbel reaching edge of pre-opercle; origin of dorsal equidistant from tip of 

 caudal and a point between occiput and posterior nares; distance between caudal and 

 anal 4.4-4.5 in the length; head 4.5-5.5; D. 13; A. 11. 



17. rivulatum (Cuvier & Valenciennes). 



gg. As under g, but "differing in its large, dark blotches." IS. poeyanum (Cope). 



ggg. Accessory caudal rays not evident; caudal emarginato; toetli cjr.ic; head 4.66; depth 7; 

 D. S; A. 6; eye in middle of the head; head longer than wide; nasal barbels reaching 

 posterior margin of the eye; maxillary barbel to the gill-opening; distance between dorsal 

 and caudal about 2 in its distance from the snout; distance between anal and caudal 5.5. 



19. barbouri Eigenmann. 

 gggg. Accessory caudal rays not conspicuous, the caudal truncate; teeth conic; head 4.85; depth 



20 The male of dispar as figured by Tschudi agrees with this. 



