898 LIFE : OUTLINES OF GENERAL BIOLOGY 



emergence of a definite race, and the origin of particular strands, 

 such as a backbone, which goes back to an early palaeozoic initi- 

 ative of life. 



Some of the living fossils are fascinatingly curious. There is the 

 New Zealand lizard (Sphenodon or Hatteria), for instance, the sole 

 survivor of an ancient race of primitive reptiles. "Lizard'', it is 

 called, but that is merely for courtesy or convenience; it is the sole 

 survivor of the ancient Cretaceous and once flourishing order of 

 Reptiles called Rhynchocephalia. It is a quaint living fossil — 

 sharing its burrow with a petrel, though that is neither here nor 

 there; it is anatomically an antediluvian, a Rip van Winkle, a 

 survival, a living fossil. Its pineal body testifies to its antiquity, 

 for it bears a third upward-looking eye 1 



Another of these venerable types is very familiar to zoologists, 

 but little known to the laity. It is commonly referred to as Peri- 

 patus, though the specialists distinguish various genera — Peripa- 

 toides, Peripatopsis, Paraperipatus, and so on : and it has an extra- 

 ordinarily wide representation in many parts of the world, such 

 as tropical America, Chili, Thibet, South Africa, Australia, and 

 Malaya. The meaning of this wide distribution is plainly that this 

 caterpillar-looking creature is of very ancient origin, and has had 

 time to colonise most countries. It lives a cryptozoic life, shy and 

 nocturnal, hiding under bark and leaves, feeding on small insects, 

 which it catches in a quite unique way by squirting jets of slime 

 from its mouth. It moves quickly, something like a millipede, and 

 coils up in a flat circle when irritated. Here, if anywhere, is an 

 archaic creature, a survivor of the ancient types of air-breathing 

 animals that advanced from an Annelid worm stock towards the 

 Tracheates, like Centipedes and Insects. It is sometimes described 

 as having the kidney-tubes of an earthworm and the air-tubes of 

 an insect, two structures never again found together in one animal. 

 Another peculiarity is that the mother Peripatus may bear the young 

 ones about before birth for longer than a mare carries her foal. No 

 fossil forms are known; indeed, such a soft-skinned land-creature 

 would not often be preserved; and yet in Darwin's sense it is fair 

 to speak of Peripatus as a living fossil. And there is another interest- 

 ing aspect to which its first embryologist, the late Prof. Sedgwick, 

 alluded enthusiastically: "The exquisite sensitiveness and con- 

 tinually changing form of the antennae, the well-rounded plump 

 body, the eyes set like small diamonds on the side of the head, the 

 delicate feet, and, above all, the rich colouring and velvety texture 

 of the skin, all combine to give these animals an aspect of quite 

 exceptional beauty." Thus a living fossil may also be a living jewel^j 

 Many other examples might be given— difficult facts for the funda- 

 mentalists ; but we must be content with these instances of the wa] 

 in which the past often lives on in the present, the old amid the no 



