328 MEMOIRS OF THE CARNEGIE MUSEUM. 



Key to the Species of Pygidium found in Southeastern Brazil. 

 a. First dorsal ray prolonged in a filament; barbels scarcely reaching the edge of eye; back uniform 



blackish, lower parts light; D. 11 ; A. 10; P. 9 49. nigricans (Cuvier & Valenciennes). 



an. First dorsal ray not prolonged; teeth incisors; origin of dorsal equidistant from tip of caudal and a 

 point between the eyes and nasal barbels. 

 b. First pectoral ray not prolonged, or with only a trace of a projection; first anal ray behind the 



dorsal; sides and back with numerous spots 50. iheringi Eigenmann. 



bb. First pectoral ray usually prolonged; first anal ray under the dorsal; markings conspicuous. 



51. zonatum Eigenmann. 

 aaa. First dorsal ray not prolonged; teeth conical. 26 



c. Origin of the dorsal nearer to the tip of the caudal than to the head, or sometimes equidistant 

 between tip of caudal and occiput in P. paolence. 

 d. Origin of the anal under the second dorsal ray, last dorsal ray over middle of anal; origin of 

 ventrals nearly equidistant from tip of caudal and snout; eye in anterior half of the head, 



near the posterior nares; head 5.5-6; D. 9; A. 7-9 52. proops (Ribeiro). 



dd. Origin of the anal under the middle of the dorsal, last dorsal ray over third anal ray; origin 

 of ventrals nearer to tip of caudal than to tip of the snout; eye just in front of the 

 middle of the head; head six times in length. 

 e. D. 8.5; A. 6.5; many faint spots, a dark streak along the middle of the sides, another 



above it 53. paolence Eigenmann. 



ee. D. 9.5; A. 8.5; a broad lateral band with serrate edges; a series of spots below it and 



another above it 54. reinhardti Eigenmann. 



ddd. Dorsal opposite the space between ventrals and anal. (See No. 59 goeldii.) 

 cc. Origin of the dorsal equidistant between the tip of the caudal and some point near the eye. 27 

 /. Pectoral ray without a filament; origin of ventral nearer snout than tip of caudal; origin of 

 anal under posterior part of dorsal; color variable; D. 7; A. 5.. 55. davisi Haseman. 

 //. First pectoral ray usually prolonged as a filament. 



g. Color plain; anal behind the dorsal; origin of ventral nearer snout than tip of caudal; 

 caudal very slightly emarginate; eye in the middle of the head; D. 11.5-13; A. 9.5- 



10.5 56. immaculatum Eigenmann & Eigenmann. 



gg. Variously marked. 



h. Origin of the anal under posterior half of the dorsal. 



i. Origin of the dorsal over the origin of the ventrals; origin of the ventrals nearer 

 tip of caudal than eye; ventrals reaching anal; D. 8.5; A. 8.5; eye in middle 

 of head; sides and back profusely covered with confluent spots, leaving the 

 ground-color in irregular vermiculations. See also .pudatissimum. 



57. vermiculatum Eigenmann. 

 ii. Origin of the dorsal behind the origin of the ventrals. 



j. Sides and back with large spots, sometimes alternating across the back; 

 origin of ventrals equidistant from snout and middle of caudal; dis- 

 tance between origin of dorsal and caudal about 1.5 in distance of 

 dorsal from the snout; caudal sub truncate; D. 10.5-11.5; A. 7.5 or 8.5. 



58. alternatum Eigenmann. 



26 Not examined in P. minvtum, nigricans, goeldii, ami punctatissimum. 



27 Not examined in P. goeldii. 



