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Show I 62 ZOOLOGY OF TilE VOYAGE OF THE BEAGLE. Mr. Darwin's collection contains two individuals of this species procured on coral reefs at the Keeling Islands. As according to his notes made from the recent fish, the posterior half of the body is bright orange, Bloc~'s figure may not be so much overcoloured as is supposed by Cuvier and Valenciennes, who state that he has represented of a bright red, what ought to be silvery grey and yellow ochre. Perhaps the colours may depend in some measure on the season. Mr. Darwin's specimens were obtained in the month of April. GENUs-STEGASTES.• Jen. Cmpus oblongo-ot,ale, compressum. Caput obt·usum. Os parvum, ltaud protmctile. Dentes maxilla1·es omnes incisores, parvi, mquales, contigui, uniseriati j palatini velutini, minuti. Ossa suborbitalia denticulata. P1·eoperculum nw1gine adscendenti levissime denticulato. Operculum inerme. Membrana brancltialis quatuormdiata. Pinnm verticales squamis confertis Jere omnino obtecta: dorsalis unica, submqualis, membranlt ad apices spinarum pamm laciniata: ventmles radio primo 1nolli elongato. Linea lateralis sub terminationem dorsalis interrupta. Squmnm 1·ost1·i et verticis parvm j operculi et corporis magnce, oblique dispositce j omnes levissime cilia tee. This apparently new form will enter into none of the genera established by Cuvier and Valenciennes. The palatine teeth serve to detach it from the Scimnidce, while this character, taken in connexion with the compressed body, and the extreme scaliness of the vertical fins, require that it should be arranged with the Cltcetodontidce, or at least have a place in that lm·ge group to which Cuvier has given the name of Squammipennes. It belongs to the second tribe in that family characterized by cutting teeth; and it would seem most nearly allied to Pimeleptents, but it does not approach that genus very closely, and may at once be distinguished from it, by the teeth being without spurs behind, and the dorsal and anal fins being more scaly. From Dipterodon, the only other genus in that tribe, it may be known by its undivided dorsal, independently of other marked differences. But though this genus requires to be arranged with the Cltcetodontidce on the grounds above mentioned, in all its other characters it comes much nearer that portion of the Scicenidce which have the lateral line terminating beneath the end of the dorsal fin ; especially Pomacentrus, which it resembles in the general form • l:nyaar1J~, tcctor, FISII. 63 of the head and b~dy, denticulated suborbi~al and preopercle, unarmed opercle, four-rayed branchwstegous membrane, and m the size and mode of arrangement of the scales on the body. I am not aware that any species of Pomacentrus have the dorsal and anal fins so completely covered with scales: but, according to Cuvier and Valenciennes, there is a species of Glypltisodon, • to which genus Pomacent1·us is closely allied, which has these fins almost as entirely scaled, as in the true Squamipinnati; and if so, there is nothing but the palatine teeth which of necessity demands the separation of this new genus from the Scicenidre. These teeth can be distinctly felt upon the vomer, hut I am not quite sure from the small size of the fish, and its mouth also being small, whether they exist on the palatines as well. It may be added that this genus shews further itself an affinity to Glypltisodon, in the filamentous prolongation of the first soft ray in the ventrals. This character is not, I believe, found in Pomacentrus. In which ever family it is placed, it forms a beautiful connecting link between the two. It is from the Cape Verde Islands. STEGASTES IMBRICATUS. Jen. PLATE IX. fig. 2. FoRM.-Oblong-oval; the body much compressed. Greatest depth rather more than one-thirJ of the entire length : head one-fourth of the same. Snout short and obtuse; the profile rising very obliquely, and forming with the dorsal line one continuous curve. The back is sharp, and appears more elevated than it really is, in consequence of the dorsal fin being thickly coated with scales, and scarcely distinguishable from the body. Ventral line less convex than the dorsal; the edge of the abdomen somewhat carinated between the ventral and anal fins, but in advance of the formet· rounded. The upper and under profile meet at the mouth at a right angle. Mouth small, and scarcely at all protractile. Jaws equal; each with a single row of cutting teeth, which are small, though rather larger below than above, even and closely set, forming a compact series: no secondary teeth behind: vomer rough with minute velutine teeth. When the mouth is closed, no portion of the maxillary is concealed by the suborbital. Eyes round, moderately large, their diameter rather less than one-third the length of the head, placed high in the cheeks, and nearer the end of the snout than the posterior angle ofthe opercle, the distance from the former being rather less than one diameter. The nostrils consist of a single minute round aperture, about half-way between the eye and the anterior margin of the suborbital. The suborbital has its margin entire as far as the end of the maxillary, at which point it curves backwards and upwards to form a narrow band beneath the eye, and the lower margin of this band is denticulated. The preopercle is likewise denticulated; but the denticulations, which are principally confined to the ascending margin, are not very obvious, and more • G. cltt'ysurua, Cuv. et Val. |