122 NEW YORK STATE MUSEUM 



(Antarctica), Polypterus and Protopterus (Gondwanaland), Lepidosiren in 

 Brazil (West Gondwanaland), and finally Amia and Lepidosteus in North 

 America (Laurentia). 



Abel in his excellent " Grundziige der Palaeobiologie der Wirbeltiere " 

 (Stuttgart, 1912), has pointed out other regions as existing Refuges or Sanc- 

 tuaries, namely, the Indo-Malay Archipelago where the Miocene vertebrate 

 fauna persists till today; central Africa where the Pliocene Eurasian verte- 

 brate fauna still persists, and the central Asiatic steppes where the European 

 glacial vertebrate fauna still survives. He asserts that these survivals are 

 not especially strong and resistent species, but weak and effeminate types 

 which have disappeared everywhere where conditions of life, changed, the 

 more resistent forms having there adapted themselves and changed to new 

 types. Inasmuch as the conditions in these " refugien '■" have not changed 

 from those of the respective former ages, it can be claimed that the animals 

 were not forced to change there, the lack of changing conditions not reacting 

 upon their oossible variability. 

 _ It is certainly true that insular forms, though more persistent than the con- 

 tinental forms show a fatal weakness as soon as they come in contact with 

 the continental types. This is shown by the rapid extinction of many insular 

 floras and faunas, as that of St Helena, New Zealand, etc., as soon as these 

 asylums are invaded by the more vigorous continental types brought there by 

 human agencies. Even faunas of isolated continents may acquire this fatal 

 weakness, as was shown by the rapid extinction of the various South American 

 ungulates in the middle Pliocene when South America became again ^ con- 

 nected with North America. In this case the invading host brought with it 

 large rapacious animals which had not been present in South America. 



There are no asylums for marine forms in the open oceans. It had been 

 claimed that the Pacific ocean, in distinction from the Atlantic ocean, con- 

 tained the old types or relicts, but Philippi has shown that all oceans contain 

 a fairly equal number of relicts. It had further been claimed or expected 

 formerly that the abyssal depths of the ocean would contain Paleozoic types. 

 The actual fauna obtained by later dredging proved to be derived from 

 Mesozoic forms, which fact had led to the conclusion that the deep oceans 

 are not older than Mesozoic time. Thus Abel (p. 4.52) has pointed to the 

 fact that all abyssal fishes belong to very young families. ^ He sees the reason 

 for the young age of the abyssal fauna in the entire extinction of the older 

 abyssal fauna through the cold waters which during and since the glacial 

 period have reached the abyssal depths. 



On the other hand although the abyssal depths do not at present contain 

 any forms that can be considered as persistent types of great antiquity, it is 

 certain that the abyssal life is in such stagnant condition that no progress 

 will take place and the entire fauna will become a persistent one. Austin H. 

 Clark in his suggestive paper, " On the Deep Sea and Comparable Faunas," 

 (Internationale Revue der gesammten Hydiobiologie und Hydrographie, vol. 

 I. Leipzig, 191.V p. 17-30, 132-46), from his study of the deep sea crinoids, 

 arrives at the following conclusion (op. oit., p. 23) : 



The ocean abysses are regions of uniform and absolutely unchanging con- 

 ditions: the temperature is very low. aporoaching the minimum at which the 

 body liquids can be maintained in liquid form ; the pressure is enormous ; 

 food, all of an animal nature on account of the absence of light, is scarce, 

 and is, as ingested, adulterated with an enormous amount of waste matter, 

 either extraneous inorganic or internal excess of liquid. Altogether condi- 

 tions are very unfavorable for animal li-fe, and of course plant life in any 

 form is quite impossible. What animal life there is, existing under absolutely 

 constant conditions, has no incentive other than internal (here as will be seen 

 reduced to a minimum) to cause it to produce variants or to eive rise tonew 

 forms, and there is not the slightest evidence that any markedly differentiated 

 new animal type ever originated in the deep sea. 



But, while the abyssal forms are now in a persistent condition, they are 

 derived from the most vigorous stocks of former faunas, according to the 

 studies of the same author, who states (op. cit., p. 134.) : 



" Thus the deep-water fauna is composed of the relics of all the previous 

 shallow-water faunas, and is in effect an incongruous and heterogeneous col- 

 lection of what were once dominant, adaptable, widely spread and exception- 



