456 Mr. C. T. Regan on 



base of dorsal ; free edge emarginate ; length of base I or 

 less than I the length of the fish. Pectorals extending to 

 the pelvics, which reach the vent. Silvery, back darker ; no 

 humeral spot ; a plumbeous lateral band ending in a blackish 

 spot which extends to the end of the middle caudal rays. 



Rio Iroquois. 



Eleven specimens, 70 to 125 mm. in total length. 



Five specimens from Western Ecuador (Fraser) should 

 be referred to this species, and it is probable that the two 

 small specimens from Panama (Bransford), recorded by 

 Eigenmann and Ogle as T. emperador, also belong to 

 T. scleroparius. 



The name Tetragonopterus simus may be restricted to a 

 species which differs from the one described above in the 

 smaller eye (f the length of head in a specimen of 72 mm.), 

 the longer anal fin (extending forward to below the dorsal 

 and measuring a little more than I the length of the fish), and 

 the absence of a well-defined black caudal spot. 



Closely allied to T. simus is T. microphthalmus, Glinth., 

 from Peru, which resembles T. simus in the small eye, but 

 agrees with T. scleroparius in the extent of the anal fin and 

 the presence of a black caudal spot. 



3. Tetragonopterus emperador. 

 Astyanax emperador, Eigenm. & Ogle, Proc. U.S. Nat. Mus. xxxiii. 



rJor, p. 26. 



Depth of body 2? to 2i in the length, length of head 4. 

 Snout shorter than eye, the diameter of which is 3 to '.)}. in 

 the length of head ; interorbital width ±\ to 2| in the length 

 of head. Maxillary extending to below anterior \ of eye ; 2 

 to 4 maxillary teeth. Suborbitals broad, the lower edge of 

 the second in contact with the lower limb of the piaoperculutn. 

 11 gill-rakers on the lower part of the anterior arch. 46 to 

 4U scales in a longitudinal series, 8 to 10 in a transverse 

 series from origin of dorsal fin to lateral line, 7 or 8 between 

 lateral line and base of pelvic fins. Dorsal 10-11; origin 

 behind the pelvics ; longest ray shorter than the head ; free 

 edge straight or convex. Anal 28-30, with 25-27 branched 

 rays ; origin below or behind end of base of dorsal ; free 

 edge emarginate ; length of base less than \ the length of 

 the fish. Pectorals extending to the pelvics, which nearly or 

 quite reach the anal. Silvery, back darker ; humeral spot 

 faint ; caudal spot extending on to the tin, but not to the end 

 of the middle rays. 



Rio Grande de Terraba. 



