HISTORY OF THE KIWI. 3 



this method must be tested and corrected at every point by the study 

 of development : it is impossible to understand thoroughly the 

 structure of any species or of any organ until we know something of 

 its becoming. As the organism develops from the simple egg-cell 

 to the complete adult, it passes rapidly through stages corresponding 

 in a general way to those which its ancestors passed through in the 

 course of their evolution, during long ages, from some simple 

 unicellular form, and it is the recognition of this principle — that 

 individual is a recapitulation of ancestral development — that has 

 given to embryology so important a place in modern biological work. 



The Kiwi — including under that name the four species of the 

 genus Apteryx — is the most anomalous and aberrant of existing 

 birds, and, living as it does only in the three islands of the New 

 Zealand group, may be considered as one of the proudest possessions 

 of our colony. 



Apteryx is sharply distinguished from all other birds by the 

 position of the nostrils which are at the tip of the long beak instead 

 of near the base. It is also remarkable for its small eyes and its 

 wonderfully perfect olfactory organs, all other existing birds having 

 large eyes and a comparatively poorly developed organ of smell. 

 The eye, moreover, differs from that of all known birds in being 

 devoid of the pecten, a plaited process of the choroid coat which 

 extends from near the entrance of the optic nerve to the back of the 

 crystalline lens. 



The Kiwi is placed, along with the Ostrich, Rhea, Emu, Casso- 

 wary and Moa, in the sub-class Ratitve, all other existing birds 

 being included under a second sub-class Carinat.e. The distinctive 

 characters of these two groups may be very briefly summarized 

 and are, for the most part, connected with the power of flight 

 possessed by the great majority of the Carinatte and the absence of 

 that power in the Ratite, which are without exception terrestrial 

 birds with extremely small and insignificant wings — quite incapable 

 of raising their usually bulky bodies from the ground. 



1. In Eatitfe the feathers are evenly distributed over the body : 

 in Carinata? they usually spring from well defined feather tracts 

 separated from one another by featherless spaces. 



2. In Carinatre there are large tail-feathers or rectrices arranged 

 in a semicircle around the blunt tail proper or uropygium (" parson's 

 nose ") : in Ratitoe there are no well denned rectrices. 



3. In Carinatce the barbules of the feathers are bound together 

 by means of microscopic hooklets so that the whole vane of the 

 feather forms a coherent membrane : in Ratita: there are no hooklets, 

 the barbules are therefore disconnected and the feathers have a 

 downy or more or less hair-like appearance. 



4. In Carinatre the breast-bone is a large transversely curved 

 bone provided with a keel for the attachment of the pectoral 

 muscles : in Ratite the sternum is usually flat and never has a 

 keel. 



