PuRNELL. — On tlie Animal Mind in Organic Evolution. 249 



own experiences of the kea's intelligence. While camped 

 upon the lower slopes of Mount Cook he and his com- 

 panions were troubled by three keas, one of which he 

 finally managed to kill with the blow of a stick ; and a 

 second, which seemed curious about the fate of its com- 

 panion, he also contrived to strike on the back, but without 

 killing it. Mr. Green proceeds, "The wisdom of these keas 

 was remarkably illustrated by the readiness with which 

 they profited by this lesson concerning a new source of 

 danger. Up to this time we had had no difficulty in 

 approaching and shooting them with the gun ; after this 

 incident they never let us come within range. The size of 

 this parrot's brain when compared with that of the ducks 

 which we shot was a source of frequent comment as we 

 prepared them for the pot, and the deficiency of brain-power 

 in the ducks was demonstrated not only by dissection, but 

 by the slowness with which they profited by the lessons of 

 experience." I do not, however, agree with Mr. Green's 

 low estimate of the intelligence of our New Zealand ducks. 



One of the most remarkable problems encountered by the 

 student of nature is the cause of the disappearance of in- 

 numerable forms of animal life'which once tenanted the globe. 

 They culminate, in numbers and diversity of structure, at 

 certain epochs, and then disappear from the world's life- 

 history, sometimes suddenly (although the suddenness may 

 be only apparent) and sometimes gradually. The dinosaurian 

 reptiles, which formed such a conspicuous feature of the 

 Mesozoic fauna, may be taken as an example. Judging 

 from the fossil remains which have been exhumed in many 

 countries, these huge and often strangely shaped creatures 

 must at one time have ranged over a large portion of the 

 land-surfaces of the Northern Hemisphere, and been very 

 abundant. Many of them were of gigantic size, far sur- 

 passing in magnitude any land animal now existing. One, 

 the Atlantosaurus, whose remains have been discovered in 

 the Jurassic deposits of the Eocky Mountains, measured from 

 80ft. to 100ft. in length; others 50ft., and so on. Their 

 skeletons, too, are of the most massive description. It would 

 seem as if no enemies outside of their own race could suc- 

 cessfully assail such monsters, and that changed surround- 

 ings could make but little difference to them. Nevertheless, 

 at the close of the Mesozoic period the dinosaurs vanished, 

 one and all. What was the cause of their sudden efface- 

 ment? Some inquirers have attributed it to the failure of 

 a sufficient supply of food, but there is no actual evidence to 

 support such a theory, and it seems inherently improbable. 

 Most of the dinosaurians were vegetable-feeders, and the Terti- 

 ary period is marked by abundance of vegetation. Moreover, 



