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Show 32 ZOOLOGY OF TilE VOYAGE OF THE BEAGLE. b . d 1 · h ces behind the pectoral and extends in like manner to the eight. In the t Ir 'w uc commen ' . d' l b h ' d h. .. fi I the fourth which commences on the breast, 1mme 1ate y e m caudal, there are t u.y- ve. n , . . . · f h t f th branchial membrane to the Jsthmus, there are tlurty, reckomng the pomt o attac men o e . . d h to behind the anal, where it unites with its fellow to form one ; between thts POt.nt an . t e caudal there are ten, the serratures of which are rather obsolete. T~e fou~th pa1r of ndges are t h roug h out tl1 e1· r course less sharply serrated than the second and third patr.s , and these las. t agam· rat he r 1e ss so tl1 an the first or dorsal pair· Between the two ventral n. dg. es, near the1. r commencemen t m· £& ron t o f the ventral fins , are six slightly serrated s.c ales (stmtlar to. those tn the ridges) forming on the breast a somewhat triangular patch, two s~ngle ones standmg first, then four others in pairs. The lateral line, which is catenulated as m A .. catapltractus, commences at the upper angle of the opercle, then bends downwards to take a mtddle course between the second and third ridges, which it preserves to the caudal. The first dorsal com~e?ces behind the seventh scale in the dorsal ridges, or at about one-third of the entire length; 1t ts of the same fofm as in the A. catapltractus, but contains more rays; its membrane terminates at the fifteenth scale, and there are rather more than two scales between it and the second dorsal, wh1ch last is rather shorter and higher than the first. The rays of the first dorsal are not stouter than those of the second, nor relatively stouter than those of the A. cataphractus. The rays of the second dorsal are simple, with the second and third rather longer than the first. The anal answers to the second dorsal. The pectorals are rounded, and one-fifth of the entire length. Ventrals very narrow, and scarcely more than half the length of the pectorals. Position of the vent a little anterior to a line connecting the extremities of the ventrals. CoLOuR.-(In spirits.) Dusky grey above and on the sides, paler beneath ; with four broad transverse blackish fascire passing across the back and down the sides as far as the third longitudinal ridge of scales. The first fascia is in the region of the first half of the first dorsal ; the second at the commencement of the second dorsal; the third near the end of the second dorsal; the fourth half way between the end of the second dorsal and the caudal ; and a little beyond this there is a faint trace of a fifth fascia. The body is a little mottled in places with spots of the same dark colour as the fascire, and the fins, with the exception of the ventrals, are of the same hue. Habitat, Chiloe, (West coast of S. America). The absence of vomerine teeth has been considered by Cuvier as one of the characters serving to distinguish Aspidoplwrus from Cottus; but as these teeth are very distinctly developed in the present species, we must rather dwell upon the large keeled sharp-pointed scales, which envelope the body in a kind of mail, and, as Dr. Richardson observes, • .. give the Aspidoplwri a totally different aspect from the Cotti." Indeed on equally strong grounds as those on which Cuvier has separated Pinguipes from Percis and P1·ionotus from Trigla, the present species, which possesses both vomerine and palatine teeth,t might be made a distinct * Faun. Bor . .A.mer. Part Third, p. 49. t Is it not possible that this may be found to be also the ca..<~C with several of the foreign species described by Cuvier, in which the absence of these teeth bo.s been rather presumed than ascertained from actual examination 1 FISH. 33 genus from Aspidoplwrus, or at least considered as one of its subgenera. But in the present uncertain state of our knowledge with respect to the exact value of this character,* and from the general resemblance of the A. Chiloensis in all its principal characters to the other species of this genus, t I have not thought this step necessary. This species was taken by Mr. Darwin at Chiloe. There are two specimens in the collection. The second differs from the one above described, only in having one ray less in the first dorsal, and two more carinated scales in each of the dorsal ridges. Independently of its having vomerine and palatine teeth as above noticed, this species will not enter into any of Cuvier's sections of the genus Aspidoplwrus, but combines in itself the characters of his first and third ; the dorsals being separated by nearly three scales, the jaws being very nearly equal, the rays of the first dorsal not stouter than those of the second, and the throat being bearded. PLATYCEPHALUS INOPS. Jen. P. capite longo, la?vi, ubi que inenni, spinis dudbus ad angulum preoperculi brevissimis a?qualihus exceptis ,· oculis magnis, m·cte p1·opinquantibus: do1'so et laterilms fuscis ,· abdomine albido ; pinna dorsali primd litura magna irregulari nig1·o-fuscd postice maculatd; dorsali secundd, caudali, et pectoralibus, maculis fuscis parvis; anali et ventralibus fere omnino nigricantibus. B. 7; D. 8-12; A.12; C. 13, &c.; P. 19; V. 1/5. LoNG. unc. 16. FonM.-Head very much depressed, and rather longer than in most of the species of this genus; its length being nearly twice its own breadth, and nearly one-third of the entire length. Breadth of the body at the pectorals one-seventh of the entire length : depth at that point half tl1e breadth. Snout rounded horizontally. Lower jaw longest. Gape reaching to beneath the • Cuvier seems to have attached much value to tho character of teeth on the palate; but I agree with Dr. Richardson, (Faun. Bar. Am. Part iii. p. 19.) in considering it " of little importance o.s a generic character in some families of fish.'' And tho author last mentioned notices an instance (exactly analogous to that of the .Aspidoplwrus Chiloenaia) in the Tltymallus sif!nifer, which, he says, "resembles the common grayling very closely in its general form, but differs from it in having palatine teeth.'' t In its general characters it docs not depart from the A. cataphractus of the British seas, anything like so much as the A. quaclricornis, and A. monopteryf!ius do. F |