2 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 point 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 striee. 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 striae ; 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. 

 Colour. — 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. 



