Cope. ] 694 [May 17, 
four teeth. The mandibular series is uninterrupted, and consists of seven 
teeth on each side, the posterior four being much smaller than the others. 
The two posterior mandibulars are incontact with the median pair of the 
anterior series, and are separated by a narrow interspace from each other. 
The general form is broadly rhombic. The depth is one-half the length 
with the caudal fin, and the length of the head enters the same three and 
one-half times. Radii; D. I. 15; A. 23; V.8;P.16. The inferior paired 
fins are very short; the others are well developed. The adipose fin is 
furnished in its superior part with jointed rays, vhe inferior portion is 
scaly. The base of the anal fin is covered with minute scales. The 
origin of the first dorsal ray is a little behind that of the ventral fin, 
and the anal begins under the last third of the former. Ventral spines 
46, all simple and recurved. Scales 26—65+6—21 ; the lateral line con- 
siderably decurved behind the head. The head is wide and depressed 
above the orbits. The latter enter the length of the head 4.5 times; 
the inter-orbital space 2.5 times, and the muzzle once, axially measured. 
The frontal region is moderately convex in cross section. The mandibu- 
lar teeth close within the premaxillaries, and the upper jaw projects be- 
yond the mandible. The lips are equal, however, in consequence of the 
thickness of the lower, which fills the space. Its superior surface is pap- 
pillose, and at the points where it comes ih contact with the maxillaries 
it is continued as a free beard on each side, reaching to below the centre of 
the nares when extended. The maxillary is folded under the preorbital, 
but its posterior border cannot reach the line of the anterior border of the 
orbit. 
Total length. M. .130; of head, .040 ; to line of dorsal fin, .055 ; to line of 
anal, .079 ; to base of caudal fin, .103. Color silvery, plumbeous above ; 
the sides marked with rather large round plumbeous spots. A silver band 
on each side of the ventral spines. Ana] fin, caudal, except superior and in- 
ferior border, and terminal halves of paired fins, black. Dorsal dusky. 
In a larger specimen, probably from Nauta (230 mm.), the scales are finely 
ctenoid, those at the bases of the median fins coarsely so. The head is fur- 
nished with minute rugosities, and there are no labial beards nor color 
spots. 
Coll. 1873-1877. 
98. MyLETES BIDENS Spix. 
Coll. 1878, 
99. MAcrRoDON TRABIRA Spix. 
Coll. 1873-77. 
100. ERYTHRINUS SALMONEUS Gron. 
Coll. 1873-77. 
101. ERYTHRINUS BREVICAUDA Gthr. 
Coll. 1873. 
102. PyrRRHULINA ARGYROPS, sp. nov. 
Radii; D. 1.9; A.1. 9. Scales in seven longitudinal, and about twenty- 
