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Show 1:2 ZOOLOGY OF TilE VOYAGE OF TilE BEAGLE. 0 -The specimen above described appears, in its present state, greyish brown, with zi~-zag OLOl~R· . d·rr t di'rections of a darker tint. A second individual is stated by Mr. Darwm to mes m weren . " b 1la ve 1u. een, wh en al'Ive , '' above salmon-coloured." A third is des.c nbed as a ove aureous- coppery, w1' th wa ve - like lines of dark brown ' which often collect mto four or fiv. e transverse bands; fins lead-colour; beneath obscure; pupil dark blue." Both these l~st specimens appear now, like the first, greyish-brown. The wave-like lines extend over a portion of the dorsal and anal fins. Habitat, coast of Northern Patagonia, and the mouth of the Plata. This species is evidently very closely a~li~d to the P_· Brasilianum ~f Cu~ier aud Valenciennes, and possibly may not be d1stmct. It differs, however, m hav~ng only two, instead of three, teeth on the basal margin of the preopercle, . wlu~h character prevails in all the specimens. It has also one or two more soft 1·ays I_D the anal. It likewise approaches the P. aculeatum of the same authors, b~t th1s last species is said to be particularly characterized by three ve.ry s?arp pomts _on the subopercle towards the lower angle, in the room of wh~ch, m the speCI~s here described, there is only one small triangular flattened pomt, rather sharp m two individuals, but in the third blunt, with the margin slightly crenated. The colours too appear to be different. . . Mr. Darwin's collection contains three specimens, wh1eh do not materially differ from each other. The largest, measuring fifteen inches in length, was taken in forty fathoms water off the mouth of the Rio Plata. The two others, smaller, and not exceeding nine, and seven and a half inches respectively, were got on the coast of Patagonia in lat. 38° 20': where it is stated that great numbers were obtained, many exceeding a foot in length. In these smalle1· specimens the canines are not so numerous or well developed as in the larger one. "One specimen when caught, vomited up small fish and a Pilurnnus. Was tough for eating, but good."-D. DIACOPE MARGINATA. Cuv. Diacope marginatn, Ou'D. et Val. !list. des Poise. tom. ii. p. 320. FonM.-Greatest depth of the body and length of the head equal, each being not quite one-third of the entire length. Nape somewhat elevated, whence the profile falls very regularly in a sligbtl)( convex line. The jaws appear equal when open, but when closed the upper one is a little the longest. Teeth velutine, with four well-marked canines in the upper jaw, two on each side of the anterior extremity, the outer one of which is longer than the inner. Opercle with two flat blunt points. Denticulations of the preopercle, particularly those at the angle below the notch, moderately well developed. Tubercle of the interopercle prominent. There are scales on the cheeks and pieces of the gill-cover, but none on the crown, snout, jaws, or suborbitals. The scales on the FISH. 13 body are moderately large. There are rows of small scales between the rays of the vertical fins, but they are more developed between the soft rays than between the spinous. The dorsal has the first spine half the length of the second, which itself is a little shorter than the third ; fourth, fifth, and sixth equal and longest; there is very little difference in the lengths of the remaining rays, nor is there much between the spinous and soft portions of the fin, which, taken as a whole: appears nearly even throughout. Anal short, commencing in a line with the fourth soft ray of the dorsal, and terminating at the same distance from the caudal as that fin: second and third spines very stout. Pectorals nan-ow and pointed, a little shorter than the head. V entrals a little shorter than the pectorals. B. 7; D. 10/14, the last double; A. 3/8, the last double; C. 17, and some short ones ;•P. 16; V. J/5. Length 6 inches. CoLoun.-'' Upper part pale lead colour: pectorals yellow; ventrals and anal orange: sides very pale yellow."-D. In spirits, the colour appears almost uniform greyish-white. The dorsal and anal fins have an edging of black, which is not noticed by Mr. Darwin, and which is characteristic of the species. The caudal is entirely dusky. There are no traces of spots on any part of the body. Habitat, Keeling Island, Indian Ocean. All the known species of Diacope are stated by Cuvier and Valenciennes, as coming from the Indian seas. The D. marginata was first brought from thence by Commerson. It was afterwards received by the authors above mentioned from Pondicherry. The expedition under Captain Duperrey, met with it at the Island of Oualan. Mr. Darwin's specimen was obtained at the Keeling or Cocos Islands : I believe it to be referrible to this species, as it possesses the characteristic black edging on the dorsal and anal fins; but as the description in the "Histoire des Poissons" is very brief, containing a mere notice of the colours, I have thought it advisable to annex that of the present individual. GENUs-ARRIPIS. Jen. Membrana brancltialis septem-radiata; apertu1·d ampld. Pinna dm·salis unica; spinis gracilibus. Dentes aculeiforrnes, tenues; serie maxillari externd cceteris fm·tim·i. Opm·cul~tm muc1·onibus duobus parvis postice armatum. Preoperculu:m marginibus basali et adscendenti denticulatis; spinis nullis. Ossa i1ifraorbitalia leviter denticulata. Os maxillare squamosurn. Squamce corpm·is levissime ciliatis, postice st1·iis levissirnis, transve1·sis, parallelis, flabelli locum occupantibus. I propose to establish this new genus for the reception of the Centropristes Gem--gianus of Valenciennes, which appears to offer sufficient peculiarities to |