6 Mr. Burton on the Natural History and Anatomy 



ter which were constantly on the wing, as ascertained by the 

 whiteness of the abdomen. 



This bird makes no nest ; it merely finds out some slight con- 

 cavity among the rocks, where there is a little sand, on which it 

 lays its egg. The young one after it is hatched is fed on fish 

 brought to it by the parent birds. 



ANATOMY. 



I shall only dwell on those parts of the anatomical structure 

 of this bird which appear most essentially to differ from that of 

 others of the same Linnaean genus ; and this is particularly the 

 case in its osteology. The bones of the head in general are thick 

 and heavy, and the cavity of the cranium extremely small in com- 

 parison with the size of the head ; so much so, that this cavity of 

 one of the genus Psittacus, of equal or even of inferior size, con- 

 tains not less than three times the quantity of brain. The ver- 

 tebrae of the neck are very numerous, and have great flexibility 

 on each other. The number of the ribs on each side is seven ; 

 the upper one is false, or unattached to the sternum ; the other 

 six are true. The process given off by the second, third, fourth, 

 fifth, and sixth, is situated about one-fourth of their length from 

 the sternum, and just before the termination of the first division 

 or joint ; it is of nearly similar breadth and thickness with the 

 rib itself, of more than half an inch in length, and descends 

 directly towards the next, lapping over its outer side. The 

 inferior rib wants this process. These appendages serve to 

 strengthen the parietes of the chest generally, to enable the ribs 

 better to support the action of the muscles, and particularly to 

 afford a more extensive surface for the attachment of the great 

 pectoral muscles, the size of which accords with the magnitude 

 of the wing. Each rib is divided into three separate portions, 

 or bones, connected to each other and to the sternum by in- 

 termediate 



