eigenmann: fresh water fishes. 259 



not prolonged ; belly rounded ; gill membranes free from each other and 

 from the isthmus. 



This genus is found in the Rio Magdalena, Rio San Francisco, in the 

 Amazon and south to the La Plata basin and from Santiago to Puerto 

 Montt on the Pacific slope. The relationship oi pisciculits, which enters 

 the Patagonian area, to the other species of the genus can be expressed 

 by the following key to the species. 



a. Maxillary with a single tooth or none. 



b. A black caudal spot ; a bright longitudinal band on the sides ; maxillary without teeth in 

 the majority of individuals ; A. 20-27, usually 21-25 ! scales 5 or 6-30 to 36-5 or 6, 

 infrequently 7 scales above the lateral line ; depth 2^ to 2| ; head 3^ to 4^ ; eye 

 3 1 to 4. intermpttis Jenyns. 



bb. No caudal spot, or the spot very obscure ; maxillary with a single tooth or none. 



c. Anal 19-22; depth 2.6; head 3.6; eye 3 in head; scales 3-32-4; D. 10; an in- 

 distinct dark caudal spot ; a bright silvery longitudinal band, monodon ' Cope. 

 cc. Anal 12-15 ; depth 3-4 ; head 3-4 ; eye 3 in head ; scales 6-33 to 36-5 ; D. 10- 

 1 2 ; a silvery lateral band, no black markings. annce McAtee. 



aa. Maxillary with more than one tooth. 



d. Anal short, of but 14 rays ; D. 10; teeth usually five-pointed ; a silvery lateral band 

 margined above with black ; depth 3-4 in the total length ; head 5 ; eye 3 in head. 



14. pisciculiis Girard. 

 dd. Anal with 19-26 rays. 



e. A black spot at base of caudal ; scales 30-32. 



/. Anal 23-26 ; no humeral spot, an intense dark violet spot on the base of cau- 

 dal and continued to the tip of middle rays ; a light yellow spot just behind 

 the dark caudal spot on the upper and lower caudal rays ; a conspicuous 

 violet stripe from behind the ventrals along the entire base of the anal, a branch 

 extending from the base of the first three or four anal rays obliquely to the 

 tip of the 6th and 7th rays and back along the remaining rays ; head 3^-3! ; 

 depth 3I-3I ; D. 9-10 ; lat. line 30 ; mouth very oblique, lower jaw project- 

 ing ; teeth numerous, very small and slender ; interorbital bones entirely cov- 

 ering the lower cheeks. nattereri Steindachner. 

 ff. Anal 21-24; no humeral spot, sometimes a rounded spot on each side of the 

 belly between the ventrals and anal ; caudal spot continued on the middle 

 rays but not reaching the end ; sometimes a black line extending forward ; 

 head 35—3! ; depth 2^-3 ; eye nearly twice as long as the snout, 2.5-2.66 

 m the head ; maxillary without teeth ; D. 9 ; scales 32-34. 



calliurus Boulenger. 



' The dorsal profile of one of Cope's types, kindly sent for e.xamination by the Philadelphia 

 Academy, is more strongly arched than the ventral and the caudal spot appears under the lens 

 as a scattered series of contracted pigment cells. In specimens at hand of intcrruptus the ventral 

 profile is more strongly arched than the dorsal, and the caudal spot is large and conspicuous ; 

 otherwise the species are very similar. 



