1878.] 689 
(Cope. 
The muzzle is acuminate and the mouth very small. The orbit is large, 
its diameter exceeding the muzzle, and entering the head four times, and 
exceeds the interorbital width by nearly its half. 
The color is plain, with the row of scales bearing the lateral line silvery 
and without dark borders. There are nine narrow rather weak vertical 
blackish bars, between the caudal fin and the occiput. Inferior fins un- 
spotted ; caudal with a dark shade at the base, and one at the extremity. 
Total length M. .029; of head, .006; to line of dorsal fin -010 ; to do, of 
anal, .018; to basis of caudal .026. 
This species is dedicated to my friend Doctor Franz Steindachner, of 
Vienna, the distinguished zoologist, who has added much to our knowl- 
edge of the fishes of the Amazon. I have derived much instruction in this 
department from his very full diagnostic analyses. 
Coll. of 1878. 
72. APHYOCHARAX PUSILLUS Giinth. 
Coll. 1878. 
73. SCHIZODON FascIATus Spix. 
Coll. of 1877. 
74. ScHIZODON SAGITTARIUS, Sp. nov. 
This species is more elongate and slender than any of the known repre- 
sentatives of the genus ; the vertical diameters of both head and body being 
reduced. The extension of length is in the post dorsal region. Length of 
head into the total, less the caudal fin, a little more than five times ; depth 
of body into the same nearly six times, hence less than length of head. 
Radii, D. I. 11; C. 2 +1942; A.I.9; V.9; P. 16. Dorsal fin origin. 
ating anterior to the point marking two-fifths the distance from the end of 
the muzzle, to the base of the caudal fin ; its elevation equal to the length of 
the head. Pectoral fin not reaching the ventral, which does not reach half 
way to the vent, and originates below the fourth dorsal ray. Orbit enter- 
ing the length of the head 4.2 times, and the interorbital width twice ; 
the inferior range of vision is a little greater than the superior. Mouth 
terminal, the mandible a little longer than the premaxillary, and armed 
with six teeth. These are smooth externally, and have two principal cusps. 
The superior are denticulate, the denticles arranged into three cuspidate 
groups. In both jaws the median teeth are larger than the lateral. Total 
length, M. .165; length of head .027; length to origin of the dorsal 
fin .051; do. to origin of ventrals .057; do. line of origin of anal fin .110. 
Above dusky to second row of scales below the lateral line; below this 
point silvery. Fins unspotted except the caudal, which has a dark longitu- 
dinal shade along the middle of each lobe. 
This species is probably allied to the Rhytidodus argenteofuscus of Kner, 
put in that species according to Kuer, the superior teeth have but one 
point, those of both jaws are keeled externally, and the depth of the body 
exceeds a little the length of the head. The inferior tooth figured by Kner 
is entirely unlike those of this fish, 
Coll. 1877. 
PROC. AMER. PHILOS. 80C. XVII. 101.4. PRINTED JUNE, 1878. 
