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Show :PISII. 3 No true perch had been obtained from South America until M. D'Orbigny discovered one in the Rio-Negro, in North Patagonia, which has been since described by Valenciennes, under the name of P. tru.clta.-. The present species was found dead by Mr. Darwin, high up the river of Santa Cruz, in South Patagonia. It is evidently very closely allied to the P. truclta, aml is spotted in a similar manner; but it appears to differ in the scales not advancing on the snout beyond the nostrils, or covering more than the posterior half of the suborbitals. Those on the body are also particularly characterized by being so smooth, as hardly to communicate any sensation of roughness when the hand is passed from the tail towards the head, though the head itself is rough. This circumstance has suggested the specific name. This species further disagrees with the one above alluded to in having the caudal slightly forked, not rounded; and in having two soft rays less in the second dorsal, and one less in the anal. Valenciennes's description, however, of the P. truclta is very brief; on which account I have been the more minute in that of the P. lce1iis. This perch, with P. truclta, would almost seem to form a subordinate division in the genus, distinguished from that embracing all the other described species, by the character of the scales covering a large portion of the head which gives it a remarkable scirenoid appearance. Both species may be known from all the North American perches, by their having the body spotted instead of banded, and by the smaller number of rays in the first dorsal. In this last character they agree with the P. ciliata, and P. ma1-ginata of Cuvier and Valenciennes. J. SERRANUS ALBO-MACULATUS. Jen. PLATE II. S. lateribus maculis albis serie longitudinali dispositis ; dentibu.s vel1dinis; paucis, !tic et iltic sparsis,fortioribus, aculeiformibus, vel Sltb-conicis; preoperculo margine adscendcnti convexiusculo, denticulato; denticulis ad et infra angulum paulo majoribus; operculo mucronibtts duobus parvis, et spinlt intermedidfm·ti, a1wtato; 1·ostro et maxillis nudis ; squamis corporis leviter ciliatis ; pinnd caudali cequali. B. 7; D.lOJ13; A. 3/7; C.I7, &c.-P.17; V. 1/5. LoNG. unc. 16; lin. 9. FoaM.-Of an oblong-oval form, with the greatest depth about one-fourth of the entire length. The dorsal and ventral lines are of nearly equal curvature. The profile is nearly rectilineal, • Hist. des Poisa. tom. ix. p. 317. I refer to the quarto edition throughout. |