1906.] NATURAL SCIENCES OF PHILADELPHIA. 325 



Characidium steindachneri Cope. Fig. 18. 



Proc. Amer. Philos. Soc. Phila., XVII, 1877-7S (Mav 17, 1878). p. 688. No. 

 21,428, A. N. S. P., type. Peruvian Amazon. 'Prof. J. Orton. Coll. of 

 1873. 



Width of head 2h in its length. Gill-opening extending forward 

 about opposite middle of pupil. Vent about last fourth in space 

 between origins of ventral and anal. Color in alcohol brownish with 

 ab&ut 9 transverse distinct dusky bars. Fins all pale brownish. 

 Iris brownish. Length about lyV inches (caudal damaged). Other- 

 wise like the preceding. 



Characidium tenuis (Cope). 



Chorimycfenis tenuis Cope, Amer. Nat., XXVII, 1894, p. 67. The upper 

 waters of the Jacuhy River, in the Brazilian State of Rio Grande do Sul. 



H. H. Smith. Cope, Proc. Amer. Philos. Soc. Phila., XXXIII, 1894 



(January 5), p. 86, PI. 5, fig. 3. 



Head 4f ; depth 6f ; D. in, 9; A. in, 6, i; scales 36 in lateral line to 

 base of caudal and 2 more on latter; 4 scales obliquely back between 

 origin of dorsal and lateral line; 3 scales obliquely back from origin of 

 adipose fin to lateral line; 3 scales from opposite origin of ventral 

 obliquely up and f on\-ard to lateral line ; 3 scales obliquely forward and 

 up from origin of anal to lateral line; 12 scales before dorsal; width 

 of head 2 in its length ; snout about 4^ ; eye 3f ; maxillar}^ 4^ ; interorbital 

 space about 5; least depth of caudal peduncle 2J; length of depressed 

 dorsal about 4; lower caudal lobe (damaged) about 4; pectoral 44-; 

 ventral 5; depressed anal 5f. Edges of trunk rounded. Gill-opening 

 extending about opposite posterior margin of orbit. Rakers about 

 5 + 7, short, lanceolate and rather well separated. Filaments a little 

 less than vertical diameter of orbit. Isthmus a little broad and tri- 

 angular. Vent about first f in space between origins of ventrals and 

 anals. Color in alcohol brownish, rather pale, especially below, and 

 side with silvery reflections. Each scale of back with darker brown 

 edgQ than shade of body-color. About 8 indistinct brownish trans- 

 verse bars. Fins pale brownish, shaded with darker, anal and ventral 

 a little lighter. Iris pale brownish. Length 2yV inches (caudal 

 damaged). Type. The other example agrees. 



This species is most closely related to C. steindachneri Cope, but 

 differs chiefly in the slightly larger eye and more slender body. 



The main character advanced for the nominal genus Chorimycterus, 

 i.e., the presence of biserial mandibular teeth, is entirely fallacious, as 

 both of the cotypes before me have but a single series in the mandible. 

 It is therefore a synonym of Characidium. 

 22 



