214 



vertebra ' are wanting. The pubis and ischium on each side have coalesced with the ilium 

 to form the lower boundary of the widely-perforated acetabulum. The pubis is long and 

 slender, joins the ischium of its own side near its lower extremity, but does not join its fellow ; 

 thus the foramen ovale is defined, but there is no symphysis pubis : the absence of this sym- 

 physis facilitates the expulsion of the large ovum with its unyielding calcareous shell. The 

 ischium coalesces posteriorly with the ilium, and converts the ischiadic notch into a foramen. 

 The caudal vertebrae are few in number, with broad transverse processes formed by confluent 

 pleurapophyses, the limits of which may still be traced. A heemapophysis is articulated to 

 the lower interspace, between the fourth and fifth caudal, and is anchylosed to the sixth. 



Presented by Prof. Owen, F.R.S. 



1107. The right humerus of an Argala (Ciconia Argala}. 



It is remarkable for its lightness, as compared with its bulk and seeming solidity ; it is, in 

 fact, a mere shell of compact osseous tissue. The orifice admitting air to its large cavity is 

 beneath the great tuberosity at the proximal end. 



Hunterian. 



1108. The left humerus of the same bird, longitudinally bisected. 



It shows the thinness of the compact walls and the loose cancellous lacework at the extre- 

 mities : filamentary processes of bone shoot more or less obliquely across different parts of 

 the cavity, serving to strengthen, like tie-beams, the thin walls, and also, being hollow, to 

 convey minute blood-vessels. The proximal half of the bone is divided longitudinally by a 

 loose cancellous partition : the decussation or anastomoses of the delicate hollow columns 

 give an open reticulate structure to the inner surface of the air-cavity at the two extremities 

 of the bone, which is highly characteristic of the class of birds. 



Hunterian. 



1109. A coracoid of a Pelican (Pelecanus Onocrotalus). 



The thin compact parietes are removed from one side, exposing the air-cavity, which is 

 traversed by the slender decussating hollow columnar processes. The economy of the dense 

 material employed in effecting the requisite strength of the bone is well exemplified in this 

 specimen : the apertures admitting the air form an open network near the proximal end of 

 the bone. 



Hunterian. 



1110. The chief metacarpal, answering to the third or 'medius/ with the slender 

 fourth metacarpal anchylosed thereto at both ends, of a Pelican (Pelecanus 

 Onocrotalus). 



A section of the thin outer parietes has been removed from one side of the principal meta- 

 carpal, showing its large and smooth air-cavity : the columnar spiculre are very few in num- 

 ber : the pneumatic foramen is circular, and situated beneath the proximal condyle. 



Hunterian. 



