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Show 1868.] DR. J. MURIE ON SALMO SALAR. 213 zontal bend, though going backwards on the carina to a variable extent. Now as to the bronchial tubes : I am not certain that the observation I make on the specimens occurring to me is reconcile-able with Yarrell's figure in the ' Linnean Transactions,' vol. xvii. 1, but I always find C. passmori with the two tubes separate, the swelling of the lower portion comparatively small, and the directions of the tubes nearly parallel, whilst in C. buccinator the swelling of the lower portion is much greater, causing the narrow tubular portions to recede widely ; and I think the difference in the breadth and figure of the tracheal rings holds good as I described it. "As to the matter of size, m y very young C. buccinator was larger than any C. passmori I have seen; and though yours are smaller, though evidently older than the one I refer to, I think confinement and being captured very young may account for this difference. Without doubt the ordinary size and weight of those the sternum of which marks them as passmori is much less than that of the others. The other characters I gave may have value, but I wait for further observations. I take m y stand on the sternum ; and now with three specimens of each species before me exhibiting varying development, but the same essential distinction, and affording proof that it is not a distinction of sex, I feel bound to maintain my species, though I will give it up on a reasonable explanation of facts. You have not yet had all the facts before you, not being aware of m y young male Trumpeter with the parts in an early stage of progress, yet showing a manifest difference from the seemingly mature C. passmori, and putting an end to the notion of the form in C. passmori being a stage of progress. I am, &c. " P.S. On looking again at your paper I fear I did not make my measuring sufficiently clear in one point, as you seem to have misapprehended me. I refer to your page numbered 12, the short paragraph near the middle of the page, respecting the sterno-tracheal elevations in your specimens as compared with mine. Now in my specimen of C. passmori and in both the other specimens which I now think belong to it, noticed in m y appended letter, the inner surface of the sternum is level; there is no bony elevation, except that at the front of the sternum forming a knob. There is no horizontal loop of the trachea in any specimen which I should call C. passmori. M y present doubts all arise from Yarrell's figure in the ' Linnean Transactions,' vol. xvii. The bronchial tubes there are certainly those of C. buccinator ; and perhaps his figure is drawn from a very young specimen of C. buccinator, as they generally attain great size when young, and in that state the horizontal loop could be only just commencing. I shall be on the look-out for further information ; but I believe we shall have no Swans this season." Dr. J. Murie exhibited some specimens of fishes illustrative of the supposed arrest of development of the Salmon (Salmo salar) when retained in fresh water. These examples had been hatched in the Society's Fish-house from ova presented by Mr. F. Buckland, in |