FISHES. 29 
their exterior margin is long and acute, though shorter than any of their soft rays, which 
bifurcate thrice, save the posterior one, which divides but twice, and the anterior only once. 
Their external margin is broad and rounded. The pectorals are a little longer than the ven- 
trals, broad exteriorly when expanded, and composed of soft and slender rays, which bifurcate 
but twice upon their length. 
Broth) ee VOSS A ROL SC 8.0 Tas Wl, bs) iG: 
The scales are well developed, minutely serrated upon their posterior margin, which is con- 
vex or rounded. Their anterior margin is subtruncated, whilst their upper and lower margins 
are almost rectilinear. Eight distinct rows may be counted between the anterior margin of the 
first dorsal and the lateral line, and from twenty-two to twenty-five beneath it and the ventral 
line. They diminish considerably in size upon the sides and belly, becoming very minute 
under the throat. The upper surface of the head and the cheeks, the suborbitals and maxillary 
are covered with them, smaller, however, on the cephalic region proper than on the cheeks, and 
quite minute on the maxillary. Those covering the opercular apparatus are again large and 
conspicuous, being nearly as large as those of the trunk. The lateral line is very conspicuous; 
there are in it from sixty-eight to seventy scales. From the upper part of the opercular appa- 
ratus it constitutes a gradually raised curve to nearly opposite the posterior portion of spiny 
dorsal; hence the curve is continued, gradually descending to nearly opposite the posterior 
margin of the soft dorsal by a series of undulations; then runs almost straightway to the base 
of caudal, along the middle of the peduncle of the tail. 
The coloration is of a golden yellow; the upper part of the flanks and dorsal region being 
brownish or blackish owing to the presence of diffused spots and macule. The fins are uni- 
color, greyish yellow. The inferior surface of the head is whitish. 
This fish is said to inhabit most of the rivers of the republic of Chile. The specimen figured, 
together with several others, was caught in a tributary of the Rio de Maypu, near Santiago. 
Plate X XIX, fig. 1, represents, size of life, Percichthys chilensis, seen in profile. 
fig. 2, is a scale of the dorsal region. 
fig. 3, a scale from the lateral line. 
fig. 4, a scale of the abdominal region. 
Figs. 2, 3, and 4 are magnified. 
PERCICHTHYS MELANOPS, Girard. 
Puate XXX, Figs. 1—5. 
Spec. cHAR. Mouth of moderate size, posterior extremity of upper maxillary reaching the ver- 
tical of the anterior rim of orbit. Palatine teeth occupying but a small area towards the an- 
terior extremity of these bones. Opercular spine not very conspicuous. Branchiostegals, six. 
Ground-color whitish, minutely and densely dotted with black; dots crowding upon the middle 
of the scales under the shape of a central blotch, giving to the whole fish quite a dark hue. 
Syn. Percichthys melanops, Grp. Proc. Acad. Nat. Sc. Philad. VII, 1854, 197. 
Duscr. This species docs not apparently attain a very large size, judging of it from the fact 
that the specimen figured is the largest of the lot collected. It bears a general resemblance to 
P. chilensis above described, having the same general shape of the head and body; but the 
peduncle of the tail being less developed, its aspect is rather more contracted. The greatest 
depth of the body, which corresponds to the anterior margin of the first dorsal fin, is equal to 
the length of head, and is contained about three times and three-fourths in the total length; 
whilst the least depth, taken on the middle of the peduncle of the tail, enters in that same 
