1869.] HUXLEY— HYPERODAPEDOJf. 151 



its most characteristic birds are the giant Dinornithidce, some of 

 which were competent to keep stride with the Brontozoum itself. 



What if this present New Zealand fauna, so remarkable and so 

 isolated from all other faunae, should be a remnant, as it were, of 

 the life of the Poikilitic period which has lingered on isolated, and 

 therefore undisturbed, down to the present day ? 



I am quite aware that a host of difficulties may be opposed to this 

 suggestion ; but these all seem to me to be rather of the nature of 

 questions which cannot be answered for want of information, than 

 of objections formidable in themselves. For example, mammals 

 existed in the Poikilitic epoch. Why did none of these inhabit the 

 New-Zealand area and survive to the present day? Again, how 

 comes it that the solitary amphibian of New Zealand is a Frog 

 allied to those of South America, and not a Labyrinthodont ? 

 And why are the freshwater fishes also allied to, and, in one ca^e, 

 specifically identical with those of South America*, instead of 

 resembling Triassic Ganoids ? 



I cannot give a direct answer to these questions, but I can show 

 that analogous difficulties exist in cases where there can be no sort 

 of doubt as to the origin of a fauna. Thus there can be no doubt that 

 the fauna of Ireland is derived from the same source as that of 

 Europe; but just as New Zealand is devoid of the class Mammalia, 

 80 is, or was, Ireland devoid of the class Reptilia ; again, there is 

 no indigenous British Ganoid or Siluroid freshwater fish, though 

 both occur in the rivers of Central and Eastern Europe. 



May it not be possible that causes similar to those which have shut 

 out whole groups of Yertebrata of the European fauna of the pre- 

 sent epoch from the British region, operated upon New Zealand in 

 the Poikilitic period and caused its fauna to represent only a fraction 

 of that of neighbouring lands ? Or may it not be possible that causes 

 such as those which determined the extinction of the indigenous 

 horse, Macrauchenia,Toxodon, Glyptodon, &c. of South America, while 

 they left multitudes of other genera alive, have similarly weeded 

 down the fauna of New Zealand, and that investigations in the caves 

 and superficial deposits of that country will yield forms which now 

 no longer exist there ? 



I mention these possibilities simply for the purpose of showing 

 how much greater value attaches to the positive similarities between 

 the New-Zealand Fauna and that of the Trias than to their negative 

 differences. 



Finally, I may remark upon the complete modification of former 

 ideas respecting the supposed poverty of life during the Poikilitic 

 epoch which has been effected by the discoveries of late years. 



It is now clear that all the five classes of the Yertebrata, viz. 

 Mammalia, Aves, Beptilia, Amphibia, and Pisces, were represented 

 at this epoch. The mammals were apparently Marsupials, not 

 Monotremes. Of the birds nothing is known. Of reptiles, we have 

 Dinosauria, Crocodilia, Dicynodonts, Lacertilia of several forms, Ple- 



* I state these remarkable distributional facts on the high authority of Dr. 

 Gunther, F.R.S. 



