PLANT-EATING BIRDS, REPTILES, AMPHIBIANS, FISHES 191 



extensile tongue. Thus every detail in form and structure in the 

 extraordinary bill of this bird seems to have its use, and we may 

 easily conceive that the black cockatoos have maintained them- 

 selves in competition with their more active and more numerous 

 white allies by their power of existing on a kind of food which no 

 other bird is able to extract from its stony shell." 



Birds accredited with the habit of feeding on honey are pro- 

 bably in most cases, e.g. in Honey-Guides (Indicatoridce) (p. 63) 

 and Humming- Birds (Trochilidce), attracted by the minute insects 

 often associated with nectar; but there are certain cases where 

 the honey itself is undoubtedly the main object for which flowers 

 are visited. A good example of this is offered by some of the 

 parrots, in which the tongue is frayed out into a sort of brush, 

 eminently suited for licking up honey. Among these are the Kea 

 (fig. 432) and Ka-ka parrots of New Zealand (Nestor notabilis 

 and N. meridionalis], and the Lories and Loriquets of the Aus- 

 tralian region. Among the latter is the Blue-mountain Parrot 

 (Trichoglossus chlorolepidotus] of Australia, which has been watched 

 sucking the honey from the flowers of eucalyptus. 



REPTILES 



REPTILES are for the most part carnivorous in habit, Croco- 

 dilians and Snakes being exclusively so, but there are some few. 

 Chelonians and Lizards which subsist upon vegetable food. In 

 the former group it is clear that the firm horny sheaths with 

 which the toothless jaws are encased arc as well suited for 

 dividing plants as the beaks of vegetarian birds. The marine 

 turtles are nearly all predaceous, but the famous Green Turtle 

 (Chelone midas) (see vol. i, p. 219) of aldermannic reputation 

 feeds upon brown sea-weeds, grazing upon such of these as are 

 completely submerged. The beak does not possess the sharply- 

 hooked tip characteristic of many of its carnivorous allies, such, 

 for example, as the Hawk's-bill Turtle (C. imbricata), which 

 derives its name from the circumstance (see fig. 58). 



All terrestrial tortoises, including some two-score species of 

 the genus Testudo, are vegetarians, as, for example, the well- 

 known Grecian Tortoise (Testudo Gr&ca) (see vol. i, p. 213), so 

 commonly seen in captivity. Here, too, are included those Giant 

 Tortoises which either now exist, or within historic times have 



