40 ZOOLOGY. 
flattened, thick at their base, and filiform towards their extremity. The upper one is a little 
longer than the lower, its tip extending to the posterior edge of the opercular apparatus, when 
stretched straightway backwards. The velvet-like teeth constitute an elongated and transverse 
patch upon the intermaxillaries. A similar area of similar teeth exists upon the symphysis of 
the dentaries, or lower jaw. The palate is perfectly smooth. The pharyngobranchials, upper 
and lower, are either smooth or provided with very inconspicuous prickles: as far as we could 
ascertain, they appeared to be smooth. The anterior nostril approximates the upper jaw, and 
is provided at its external edge with a flattened (at base) and filiform (at tip) barbel, and about 
as long as the upper buccal. The posterior nostril, situated a little behind the anterior, is a 
little larger than the latter, and provided anteriorly with a very low and thin membrane. The 
eyes, which are situated towards the upper surface of the head, and far apart, are very small 
and somewhat elongated, nearly equidistant between the margin of the upper jaw and the pos- 
terior edge of the opercular apparatus. The cheeks are smooth, like the upper surface of the 
head, and the opercular apparatus concealed under the skin exhibits only a small group of 
prickles, situated at the upper angle of the opercle. The subopercle is largely developed, and 
its surface is covered with very conspicuous club-shaped prickles. The branchiostegal rays are 
entirely concealed under the subopercle. They are six in number; the four innermost flat- 
tened—all being enclosed in a tough membrane which projects beyond their tips. The 
branchial apertures are continuous, but not split under the hyoidal apparatus. The dorsal fin 
is situated far back ; its anterior margin being much nearer to the posterior extremity of the 
caudal than to the tip of the snout. It is nearly as high anteriorly as its base is long; the 
height of its posterior margin is less than the half of the anterior margin. Its upper margin is 
subconvex. The origin of the anal is situated opposite the posterior third of dorsal. It is 
nearly twice as deep as the extend of its base, and exteriorly convex. The tips of its central — 
rays consequently extend farther backwards than those of the dorsal, without, however, reaching 
the base of the caudal. The latter constitutes about the eighth of the entire length. It is 
posteriorly subemarginated, with its lobes rounded. There are numerous rudimentary rays 
which contiibute to give to the extremity of the peduncle of the tail a dilated appearance. The 
ventrals are situated in advance of the dorsal; their posterior extremity reaching a vertical line 
which would pass immediately in advance of the anterior margin of the last mentioned fin. 
The ventrals themselves are small and convex exteriorly, their tips not reaching the vent, 
which is situated somewhat in advance of the anterior margin of the anal fin. The pectorals 
are likewise short, broad, and rounded exteriorly, their insertion being almost horizontal, and 
below the middle line of the body. 
Br. VI; D 13; A8; C10. 1. 6.5.19; V5; PY. 
The anterior three rays of both the dorsal and anal fins are simple and shorter than the 
fourth, the first being quite rudimentary. The anterior ray of the ventrals and pectorals is 
simple also, and enclosed in a thick membrane. The central rays of all the fins are bifurcated 
three times upon their length. The lateral line is very inconspicuous, and visible only upon 
the anterior third of the body, where distant pores may be followed from the upper part of the 
opercle towards the middle of the flanks, after a slight convexity upwards at its origin. The 
skin is otherwise perfectly smooth. It is needless to add that a thick layer of mucosity covers 
the whole body, the head, and the fins. 
The ground-color is either yellowish or brownish, with small purplish macule spread all 
over the head, where they assume a cloudy aspect; also over the body, along the sides of which 
obsolete longitudinal stripes are to be seen. Two other stripes, more indistinct still, along the 
dorsal line, from nape to origin of dorsal; and three along the sides, the middle one of which 
running along the middle region of the body and tail. The inferior surface of the head and 
the belly are of a soiled yellow hue. The barbels and the fins are greyish yellow. , 
Specimens were caught in the Rio Mapocho, near Santiago. 
