The Story of the Rocks 



ii^ 



Apteryx, or the kiwi of New Zealand, a country which in 

 its fauna is a sort of old curiosity shop, retaining such relics 

 of the past as the Port Jackson sliark, the tuatara, the kiwi 

 and until recently the moas. Yet a further legacy from his 

 reptilian ancestry did Archaiopteryx possess. This is a set 

 of abdominal ribs, or rib-like bones in the ventral wall of the 

 abdomen, which he shared in common with the New Zealand 

 lizard and the crocodile. 



As to how birds took to flying we of course have no certain 

 knowledge. But we have some very ingenious and interesting 

 theories. In the first place what was the probable origin of 

 the feathers? A feather consists of a central shaft or quill 

 from which extend two rows of branches or barbs, and these 



Part of a Feather 

 Showing shaft, barbs, barlniles and liooks. Original. 



in turn give rise to a series of little barbs or barbules which 

 interlock with one another by means of rows of small hooks; 

 the whole forming a firm resistant membrane serving as a 

 propeller in the case of the wing feather, a rudder in that 

 of the tail feathers, and a protective and insulating covering 

 for the general body surface. At the base of the quill is a 

 small papilla or projection of the dermis, or lower layer of 

 the skin, which carries nerves and blood vessels and serves to 

 nourish the growing feather. The feather itself arises as a 

 tube of modified horny cells derived from the epidermis, or 

 outer skin layer, whicli splits into several parts in develop- 

 ment, which spread out to form the barbs and barbules. This 



