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Show I I I 60 ZOOLOGY OF TilE VOYAGE OF TilE BEAGLE. to form a point backwards. Caudal forked nearly to its base ; the lobes much elon.gated; the upper one, which is a trifle longer than the lower, contained rat~er more than three times and a half in the entire length. Pectorals narrow and pointed, a httle shorter t~an the head, and contained not quite four times and a half in the entire length ; fifth and s1xth . rays longest. Ventrals attached a little behind the pectorals, and not much more than half their length ; the spine about three-fourths the length of the soft rays, and scarcely stouter ~han the third spine in the anal : the axillary elongated scale three-fourths the length of the spme. The scales on the body of this species are not materially different from those of the G. Plumieri described in the "Histoire des Poissons." B. 6; D. 9/10; A. 317; C. 17, &c.; P. 16; V. 1/5. Length 7 inches. CoLOUR.-" White, silvery."-D. The fins are yellowit:Jh; the membranes here and there dotted with black: the lobes of the caudal are bordered internally with dusky. I see no trace of the interrupted longitudinal bands spoken of by Cuvier and Valenciennes, neither is there any allusion to them in Mr. Darwin's notes taken from the recent fish. Habitat, Keeling Island, Indian Ocean. I do not feel confident as to this species being, any more than the last, identical with that to which I have referred it. It requires an inspection of a large number of specimens in order to ascertain the true value of characters. The present one agrees with what is stated of the G. Oyena by Cuvier and Valenciennes, excepting that the second anal spine, which they represent as shorter than the second dorsal spine by one-half, is here shorter by one-third only: also, as mentioned above, there is no appearance of any longitudinal bands. There is no other species in the " Histoire des Poissons," to which it approaches more closely. But comparing it with Riippell's figure, if this last be scrupulously exact, there are a few other differences besides those already alluded to. Thus the fi1·st anal spine in Mr. Darwin's specimen appears shorter in relation to the second, and this last stouter as well as longer. Also the soft rays of this fin gradually decrease, giving a sloping direction to the margin, whereas in Riippell's figure, all the rays are nearly of the same length, and made equal to the second and third spines. The caudal lobes, likewise, appear longer in Mr. Darwin's specimen. It must be left for others to determine whether these discrepancies are indicative of a specific difference or not. As regards the geographic range of the G. Oyena, I know not that there is any thing in this respect to render its identity with the species here described improbable. It inhabits the Red Sea; and is also said to be common at the Mauritius ;-whence it may very possibly FISIT. 61 extend as far eastward as the Keeling Islands, where Mr. Darwin's specimen was obtained. The Sparus erytlu·urus of Bloch (pl. 261) is so extremely unlike the present species both in form and colours, that, except on the authority of MM. Cuvier and Valenciennes, who state that they had seen Bloch's original specimen, no one could have suspected that the figure had been intended for it. FAMILY-CHJETODONTIDJE. CH.IETODON SETIFER. Bloclt. Chrotodon setifer, Bloch, Ichth. pl. 425. fig. 1. -----Ou'IJ. et Val. Ilist. des Poiss. tom. vii. p. 58. FoaM.-Tbis species is one of those characterized by a prolongation of a portion of the soft dorsal fin. In the present specimen it is the sixth soft ray which is thus prolonged. The total length of this ray, measured from the root, is half the entire length of the fish; and that portion of it which exceeds the adjoining rays is rather more than half. Although the preopercle can har<.Ily be called denticulated, yet there are some faint traces of rudimentary denticulations at the lower angle. The general form, in all other respects, agrees with the descriptions of Cuvier and other authors. D. 13;24; A. 3j21; C. 17, and 6 short; P. 16, the first short; V. 1/5. Length 6 inc. 3 lines. CoLoua.-" Body pale, with narrow dark straight lines which form network: across the eye a black band : posterior half of the body bright orange : upper part of the prolongation of the dorsal fin edged with black, and a round patch of the same."-D. The black ocellus extends from the fifth to the thirteenth ray of the soft dorsal. There is no trace of the four red or yellow streaks said by Cuviet· and Valenciennes to cross the forehead from eye to eye; but probably they are effaced by the action of the spirit. A second specimen only differs from the ahove in being smaller, measuring in length not quite five inches; in having the fifth (instead of sixth) ray in the soft dorsal prolonged; and in the ocellus extending from the fifth to the tenth ray only. In the last two respects it agrees better with the description in the 1 Histoire des Poissons.' The filamentous ray terminates in an extremely fine hair, which leads me to think that the extreme portion of this ray in the first specimen has been broken off. Habitat, Keeling Island, Indian Ocean. |