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Show 1876.] ON THE ANATOMY OF PLOTUS ANHINGA. 335 skin had been destroyed by moth. The present was therefore the first authentic introduction of the Surnia ulula into this country. The Hawk-Owls of America and Europe were, Mr. Sharpe said, scarcely distinct species, but tolerably recognizable races. Tne following Papers were read :- 1. Notes ou the Anatomy of Plotus anhinga. By A. H. G A R R O D , M.A., F.Z.S., Prosector to the Society. [Received March 31, 1876.] (Plates XXVI., XXVII., XXVIII.) The Darter is one of those birds whose anatomy, with the exception of its skeleton, is comparatively little known ; I therefore take the present opportunity of describing the organs aud some of the most important muscles of Plotus anhinga from the two specimens which were recently living in the Society's collection, and which, from my prosectorial advantages, it has been my good fortune to be able to dissect. On December 28th, 1872, the Society became possessed, for the first time, by purchase, of a male specimen of Plotus anhinga, which died on the 17th of this month, with general jaundice and distention of the gall-bladder from obstruction of the common bile-duct. The second specimen, a female, was purchased on the 30th of September, 1875; it was never quite healthy, and died on the 7th of February, without any special organic lesions, but with a dropsical condition of the subcutaneous areolar tissues, frequently found in Steganopod birds. It is this second specimen which I first dissected; and the other coming to hand, opportunely for me, has enabled me to verify m y observations. Pterylographically, there is nothing for me to add to the results arrived at by Nitzsch *. The skin is not in the least pneumatic, in which respect it contrasts greatly with Sula and Pelecanus, and agrees with Phalacrocorax. With reference to the anatomy of its circulatory organs, it is to be noted that Plotus anhinga possesses only a single carotid artery, the left. In Sula bassana, Phalacrocorax carbo and P. lugubris, Fregata aquila, and Phaethon there are two. In Sula fusca (a specimen in very bad immature plumage from Port Lemon, Porto Rico) the left carotid only exists, as also in Pelecanus rufescens and P. onocrotalus. As to the respiratory organs, from Plate XXVIII. fig. 3 it can be seen that the syrinx is in no way peculiar, a single pair of intrinsic lateral muscles being present. By the side of it I have figured the lower portion of the windpipe of a male Gannet (Sula bassana), in which a pair of fatty bodies are developed just above the bifurcation of the bronchi, the like of which I have not elsewhere seen. * Pterylography, Ray Society's Translation, edited by P. L. Sclater, F.R.S., p. 151. |