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Show FISH. 105 crenatures. Lateral line interrupted; its first portion at the depth of two and a half rows of scales beneath the dorsal, and stopping beneath the commencement of the soft part of that fin ; recommencing three rows lower down, exactly in the middle of the depth, whence it runs straight to the caudal. Dorsal commencing above the opercle; the spinous portion of nearly uniform height, and scarcely more than one-fifth of t.he depth ; the soft portion much higher, and terminating in a sharp point behind. Anal answering to the posterior half of the dorsal, terminating opposite to it, and similarly pointed; with six spines, which, as well as the dnrsal spines, are furnished with very conspicuous filamentous tags. Caudal nearly even. Pectorals rounded, but not very broad, their length rather mo~e than three-fourths that of the head; the rays rather slender. Ventrals pointed; the first soft ray elongated, and reaching to the anal when laid back; the last ray attached at its base by a membrane to the abdomen. Rows of small scales between the rays of the caudal at the base of the fin ; and a few small ones along the base of the dorsal and anal, more particularly on the soft portions. CoLOUR.-" Above, greenish black; the sides paler; slightly iridescent."-D.-In spirits it appears of a nearly uniform brown all over, fins included. Habitat, Maldonado, Rio Platn. Mr. Darwin obtained this species at Maldonado, in a lake of fresh water, said sometimes to be a little brackish. It appears to belong to the genus Cltromis of Cuvier, placed by him amongst the Lahridce, but having evidently very strong affinities to some of the Scicenidce. It differs essentially from the C. Brasiliensis of Quoy and Gaimard,* in having six anal spines, and being destitute of all markings and spots. I am not aware that it is described by any author. l. ScARUs CHLORODON. Jen. PLATE XXI. S. a!7'Uginoso cyaneus, capite et pinnis ftavo-vittalis : maxillis exterius lcevibus, mm·ginibus crenatis ; caninis ad ang'ulos m·is nul/is : frmtte gradatim pt·oclivi: linea laterali tubis pm·um ramosis: squatnis uhique stt·iato-granulatis: pectoralibus acuminatis, mdiis superiorihus m·cuatis: caudali radiis exlernis cceteris longioribus, acuminatis. D.9/10; A.3/9; C.l3.&c.; P.15vell6; V.l/5. LoNG. unc. 16. FoRM.-Of an oval form; the greatest depth one-third of the length, caudal excluded: dorsal and ventral lines equally convex. Head a little less than the depth of the body, not gibbous in front, but with the profile falling regularly and gradually from the commencement of t.he do~al. Snout rather pointed. Jaws equal, their outer surface smooth, but crenated o~ t~e1r euttmg edges. No spinous canines at the corners of the mouth. Eyes rather small, t~e~r diameter not one-fifth the length of the head, situate above the middle of the cheek, but eqmd1stant from the posterior lobe of the opercle and the extremity of the snout. Snout in front of the eyes, and • Freycinet VoyOf!e, (ZoolofJie) p. 286. p |