12 
U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
its cleft directed obliquely upwards ; tbe lower jaw longest, as in Ambloplites. The posterior 
extremity of the maxillary is broadly expanded, extending to a vertical line drawn immediately 
behind the orbit. The outer maxillary teeth form quite a conspicuous row in either jaw. The 
tongue is broad and fleshy ; the teeth along its middle surface constitute an irregular band. 
The posterior nostril is much larger than the anterior one, and is situated close to the orbit, 
whilst the latter is nearly midway between the anterior rim of the orbit and the margin of the 
upper jaw. The eye is large and circular ; its diameter enters a little short of five times in the 
length of the side of the head. The external edge of the opercular bones is entire and smooth ; 
their surface is covered by large scales. The whole surface of the cheeks is similarly scaly, the 
scales being but a little smaller than on the opercular apparatus. The branchial apertures are 
continuous under the throat; the branchiostegals number six on the right side and five on the 
left. 
The dorsal fin is composed of ten spiny rays and ten soft and articulated ones, although the 
spinous portion occupies the two-tliirds of the base of the fin. The spines increase slightly in 
height towards the fourth, fifth, and sixth ; hence, posteriorly, they are nearly equal. The 
soft rays are a good deal higher than the spines ; and so are the soft rays of the anal, nine in 
number, preceded by three stoutish spines only. The caudal fin constitutes the sixth of the 
entire length ; it is sub-emarginated posteriorly, and composed of seventeen rays and a few rudi¬ 
ments. The insertion of the ventrals takes place opposite the base of the pectorals, and some¬ 
what in advance the origin of the dorsal fin. When brought backwards, their extremities do 
not extend as far as the vent, which is placed near the anterior margin of the anal. Five soft 
and articulated rays, with one spine, are the usual number in these fins. The pectorals are 
longer than the ventrals, for, their posterior extremities reach almost to a vertical line intersect¬ 
ing the vent. 
Br. VI: V. D X, 10 ; A III, 9 ; C 4, 1, 8, 7, 1, 3 ; V I, 5 ; P 15. 
The scales, inconspicuously pectinated, are quite large, deeper than long, subciliated pos¬ 
teriorly, and provided with diverging furrows upon their anterior section only. Twenty-two 
series may be observed upon the line of greatest depth, fifteen below the lateral line, and six 
above. The lateral line itself is arched and concurrent with the dorsal line, and nearer to it 
posteriorly than anteriorly. The scales upon the nape or fronto-occipital region, are but a little 
smaller than on the dorsal region properly so called. Under the thorax they are likewise well 
developed, though smaller than elsewhere. The soft portions of both the dorsal and anal fins 
are provided with irregularly attenuated scales upon their base, in the same manner as the 
caudal. 
The ground color is reddish brown, darker above than beneath. The head is irregularly 
spotted with darker brown. The centre of each scale being provided with a blackish spot, the 
general appearance of the fish is quite dark. The fins themselves are dark and obsoletely 
spotted. A large black patch is to be seen at the upper and posterior angle of the operculum. 
References to figures .—Plate III represents Calliurus melanojos size of life, adult and young. 
Fig. 1, the adult from Leon river. Fig. 5, the young, from Bio Medina. Figs. 3 and 6, scales 
from the dorsal region. Figs. 2 and 7, scales from the lateral line. Figs. 4 and 8, scales from 
the abdominal region. 
