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Show 1892.] MR. R. LYDEKKER ON A SIRENIAN JAW. 77 the Society's Gardens, where several species of the Ground-Pigeons 1 have bred repeatedly, the young of the Ground-Pigeons when hatched are nearly naked and quite helpless, and differ in no respect from the young of the typical Columbae. In proof of this I exhibit two specimens of the young of the Partridge Bronze-wing Pigeon {Geophaps scripta), hatched in the Gardens on June 7th last, and about 14 days old when they died. It will be observed that at this date they were barely covered with feathers and hardly fledged. In fact one of them was actually killed by falling from a slight elevation in the Aviary, having been hatched in the nest of a Barbary Turtledove {Turtur risorius), to which the egg had been removed in consequence of the bird that laid it refusing to sit upon it. It cannot therefore be said that these birds are " able to run soon after birth." Nor, in the reference given by Dr. Sharpe, does Mr. Gilbert, so far as I can gather from his remarks, say so; he merely states that " the young bird on emerging from the egg is clothed with down like the young of the Quail" (Gould's 'Handbook to the Birds of Australia,' vol. ii. p. 134). I cannot therefore allow that on this ground there is any justification for the important step that Dr. Sharpe proposes to take. As regards the other point put forward by Dr. Sharpe in justification of his proposal, it is no doubt the fact that the sternum of the Australian Ground-Pigeons is longer and narrower than the corresponding organ in the typical Columbae. But the general characters of the sternum in Geophaps and its allies remain the same as in the typical Columbae, so that on this point also I see no sufficient ground for the alteration proposed. I prefer to keep all the Columbae together, as heretofore, in one group of ordinal value, as constituting a very well-defined and very natural division of the class of Birds, and I even doubt whether more than one family can be properly made of them. . The following papers were read :- 1. On a remarkable Sirenian Jaw from the Oligocene of Italy, and its bearing on the Evolution of the Sirenia. By R. LYDEKKER, B.A., F.G.S. [Eeceived December 9, 1891.] Among a series of Tertiary Vertebrate fossils recently acquired by the British Museum my attention was specially directed to one labelled by the dealer from whom it was received, " Sirene, Oligo-caen, Monte Grumi, Vicenza." At the first glance I felt convinced that the assignation of the specimen to the Sirenia was correct; but, at the same time, one of the two teeth contained in the specimen struck m e as presenting a peculiarity of form such as I had never seen in any other Sirenian. Further examination led me to the conclusion that the specimen had an important bearing on the 1 Viz.: Ocyphaps lophotes, Phaps chalcoptera, Leucosarcia picata, Phlogmnas crinigera, Calcenas nicobarica, and others. See List of Vertebrate Animals (1883), pp. 459 et seqq. |