80 Transactions. — Zoology. 



whiskers of a cat, and its hearing is known to be marvellously 

 acute. 



Mr. A. E. Wallace, in his admirable work on "Darwinism,"' 

 says (at page 114), " So soon, however, as we approach the 

 higher and more fully developed groups, we see indications of 

 the often-repeated extinction of lower by higher forms. This 

 is shown by the great gaps that separate the mammalia, birds, 

 reptiles, and fishes from each other ; whilst the lowest forms 

 of each are always few in number and confined to limited 

 areas. Such are the lowest mammals — the Echidna and 

 Ornithorhynchus of Australia ; the lowest birds — the Apteryx 

 of New Zealand and the cassowaries of the New Guinea 

 region ; while the lowest fish — the Amphioxus or lancelet — is 

 completely isolated, and has apparently survived only by its 

 habit of burrowing in the sand. The great distinctness of 

 the carnivora, ruminants, rodents, whales, bats, and other 

 orders of mammalia ; of the accipitres, pigeons, and parrots, 

 among birds ; and of the beetles, bees, flies, and moths, among 

 insects, all indicate an enormous amount of extinction among 

 the comparatively low forms by which, on any theory of evolu- 

 tion, these higher and more specialized groups must have been, 

 preceded." 



Now, whilst accepting Mr. Wallace's general argument 

 and admitting its soundness, I must venture to differ entirely 

 with that distinguished scientist as to the position assigned to 

 the genus Apteryx. I cannot for a moment admit that the 

 Kiwi is one of the lowest birds in the sense implied. It 

 rather seems to me to be an extremely specialized form, and 

 one to which Mr. Wallace's own felicitous remarks (at page 

 105) are specially applicable : "In species which have a wide 

 range the struggle for existence will often cause some indi- 

 viduals or groups of individuals to adopt new habits in order 

 to seize upon vacant places in nature where the struggle is 

 less severe. Some, living among extensive marshes, may 

 adopt a more aquatic mode of life ; others, living where 

 forests abound, may become more arboreal. In either case 

 we cannot doubt that the changes of structure needed to adapt 

 them to their new habits would soon be brought about, 

 because we know that variations in all the external organs 

 and all their separate parts are very abundant and are also 

 considerable in amount. That such divergence of character 

 has actually occurred we have some direct evidence." By 

 way of illustration, Mr. Wallace reminds us that Madeira,, 

 like many other oceanic islands in the temperate zone, is 

 much exposed to sudden gusts of wind, and that, as most of 

 the fertile land is on the coast, insects which flew much would 

 be very liable to be blown out to sea and lost. Year after 

 year, therefore, those individuals which had shorter wings, or 



