150 Zoological Society. 



This table is large enough for all reasonable purposes ; and its re- 

 sults are very striking, and cannot have had their extreme uniformity 

 caused by chance. If we leave out all those birds which, for swim- 

 ming and especially diving purposes, have the sacrum extremely long 

 and much anchylosed, such as the Sifters, Grebes, Loons, Cor- 

 morants, and also the Ostriches (excluding the Apteryx), we shall 

 have four post-acetabular joints as the medium number. A large 

 proportion of all birds have exactly four vertebrae in rear of the 

 thigh-bones ; many have only three, and about as many more have 

 five. As a rule, the small birds of a group have the tendency to drop 

 a joint occasionally ; thus the little Estrelda has one less than the 

 other Finches, the Dotterel one less than the other Plovers, and the 

 Crake one less than the other Rails. The medium- sized rapacious 

 birds, both nocturnal and diurnal, have only three. Now, if we con- 

 sider that all the vertebrae above four in the posterior part of the 

 Duck's pelvis really belong to the tail, then, as I long ago found, the 

 ploughshare-bone is composed of ten segments, as four of the ap- 

 parently sacral bones are really caudal ; and as there are eight inter- 

 mediate vertebrae, the large number of twenty-two is obtained — one 

 more than the Archecopteryx possesses according to Professor Owen's 

 method of enumeration. 



Also in the Palamedea two of the anchylosed bones belong to the 

 tail ; there are six free bones, the last having had a rather late ad- 

 dition in the penultimate joint, so that it may be considered as 

 eleven : this gives us nineteen caudal vertebrse for the subject of this 

 paper — only two less than in the Archceopteryx. The same method 

 gives us twenty-four for the Swan, sixteen for the Emeu, and twenty- 

 two for the Cormorant. 



That five of the so-called sacral vertebrse of the Palamedea belong 

 to the dorso-lumbar region is evident, because the first three have 

 hsemapophyses reaching the sternum, and on the right side there 

 are two more sternal ribs in a rudimentary condition. There are 

 seventeen vertebrae fused together, five of which must be supposed 

 removed from the front part and two from behind, thus leaving ten 

 proper sacral vertebrae. 



In small birds and in birds of the higher types with short pelves, 

 the number of true sacral vertebrae will be only about seven on an 

 average — a common number among the large herbivorous Mammalia. 



As I have only touched upon the points of interest in this skeleton, 

 when I have acquired a fuller knowledge of it and of its congeners, 

 and of the bearings and relations of the feathered tribes generally, 

 I hope to take it up again. Certainly amongst living birds there 

 is not one possessing characters of higher interest ; none that 1 am 

 acquainted with come nearer, in certain important points, to the 

 Lizard ; and there are parts of its organization which make it very 

 probable that it is one of the nearest living relatives of the marvel- 

 lous ■^/•c^tcop^erya;*. 



* The cup-and-ball joints in the dorsal region of many water-birds and of the 

 Parrots must be looked upon as a general reptilian character ; so also the single 

 head of the " os quadratum" in the Ostriches. The very simple palatines of the 

 latter birds and of the Palamedea, the very long free toes and the simple ribs of 

 the Screamer, all these are more properly lacertian. 



