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ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
the ascending margin finely denticulated, the teeth almost disappearing at the top; towards 
the angle the teeth become stronger and pomt downwards; they are also stronger and more 
scattered along the basal margin, inclining here a little forwards. Opercle with two flat sharp 
points, one a little below the upper angle, the other about the middle and terminating the gill 
cover. Both the subopercle and interopercle have their margins obscurely denticulated: the 
margin of the former is rather sinuous, and passes obliquely forwards and downwards to form a 
continuous curve with that of the latter. Crown, forehead, upper part of the snout as far as 
the connecting line of the nostrils, posterior half of the suborbitals, cheeks, and all the pieces 
of the gill cover, excepting the lower limb of the preopercle, covered with small scales, which 
are in most instances ciliated with a varying number of denticles, and feel rough to the touch : 
the extremity of the snout, anterior portion of the suborbitals, maxillaries, and lower jaw are 
naked. Above each orbit is a small semi-circular granulated plate, with the granulations dis- 
posed in striae, The suprascapulars terminate in an obtuse projecting point. The humeral 
bone forms a large osseous triangular plate above the pectorals, the salient angle terminating 
in three small teeth. Course of the lateral line a little above one-third of the depth till it 
arrives beneath the second dorsal, where it bends down to half the depth. Scales on the body 
larger than those on the head, of an oblong form, rounded at their free edges, which are 
scarcely at all ciliated, and for the most part quite smooth to the touch ; their concealed por- 
tion not wider than the free, with a fan of fourteen strie ; the rest of their surface more finely 
striated. The first dorsal commences a little beyond a vertical line from the termination of the 
humeral plate, and is almost continuous with the second, being only separated by a deep notch; 
the space occupied by the two dorsals together is exactly one-third of the entire length : spines 
strong ; the first scarcely more than one-third the length of the second, which is very little shorter 
than the third ; this last longest, equalling rather more than half the depth; rest of the spines 
gradually decreasing to the last, which is of the same length as the first. The second dorsal 
commences with a slender spine, not half the length of the first soft ray, which last is simple, 
the others being branched; third and fourth soft rays longest; the succeeding ones slowly 
decreasing to the last, which is rather more than half the longest. Anal preceded by three 
spines, the first of which is very short; second much longer and very stout ; third of about the 
same length as the second, but much slenderer; the first and second separated by a wide mem- 
brane from the third, which is closely united to the first soft ray; these last longer than those 
of the second dorsal, but in other respects similar. The anal and second dorsal terminate in 
the same vertical line ; and the last ray is double in both fins. Between them and the caudal 
is a space equalling one-fifth of the entire length. The caudal is slightly notched. The pec- 
torals are rather pointed, their length equalling two-thirds that of the head. Ventrals imme- 
diately beneath them, and of about the same length ; the first soft ray longest, and more than 
twice the length of the spine which precedes it. 
Cotour.—In spirits this fish appears yellowish brown, deepening on the back but becoming paler 
on the belly, and covered all over with small dusky spots, one occupying the base of each 
scale. 
Habitat, Santa Cruz River, Patagonia. 
