1892.] MR. R. LYDEKKER ON A SIRENIAN JAW. 77 



the Society's Gardens, where several species of the Ground-Pigeons ^ 

 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 Barhary 

 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 'Hand- 

 book 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 justi- 

 fication 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 

 E. Lydekker, B.A., F.G.S. 



[EeceiTed 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, Ohgo- 

 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 me 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 



^ Viz. : Ocyphaps lophofes, Phaps chalcoptera, Leucosarcia picata, PMogcenas 

 crlnigera, Caloenas nicobarica, and others. See List of Vertebrate Animals (1883), 

 pp. 459 et seqq. 



