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Show 1868.] ON THE DEVELOPMENT OF THE SALMON. 24 7 (thirdly) a small canine, (fourthly) a very large canine fitting into a groove of the upper jaw, (fifthly) at some distance from the preceding a smaller canine corresponding to the upper posterior canine, and followed (sixthly) by a series of closely set small teeth*. The upper jaw overlaps the lower slightly, the maxillary extending far behind the eye, which is rather small, placed in the middle of the depth of the head, nearer to the snout than to the gill-opening. Suborbital slightly and irregularly striated. Origin of the dorsal fin nearer to the end of the snout than to the root of the caudal, its last ray being opposite to the origin of the anal fin. Pectoral extending beyond the root of the ventral, ventral scarcely reaching the vent. Operculum very narrow; a naked space between the suborbital and lower limb of the opercle. Coloration uniform ; a black spot on the end of the lateral line. Two examples, 10 inches long, were collected by Mr. Bartlett at Xeberos. TETRAGONOPTERUS MELANURUS, Bl. Specimens from Surinam have the caudal fin whitish, with a broad black median band: MYLETES DUR1VENTRIS, Cuv. D. 15-16. A. 33-34. Abdominal spines 39-48. Xeberos. CYNODON PECTORALIS, Gtlll*. D. 45-48. Xeberos. XlPHORHAMPHUS FALCIROSTR1S, Cuv. A. 22-27. Young, with a blackish longitudinal band. Xeberos, Pebas. 6. O n the Supposed Arrest of Development of the Salmon when retained in Fresh water. By J A M E S M U R I E , M.D., F.L.S., F.G.S., Prosector to the Society. (Plate XXIII.) Introductory Remarks.-Lately there was brought to me a small fish of which the life-history is somewhat peculiar. So interesting, indeed does it seem to m e that I have not hesitated in bringing the facts of the case before the notice of this Society. I. do so the more readily because it appears to m e that, if it could be shown with certainty that the said fish is an undoubted Salmo salar, Linn., a physiological law of wide import would necessarily follow. * I have given this detailed description of the dentition because the other rcies referred to C//nopotanius have another series of small teeth within the outer This is another proof that Cynopotamus is not a distinct genus. |