26 



KNOWLEDGE 



[December 2, 1889. 



Cheshire, the under surface of the chest was protected hy 

 three large bony plates ; while in some cases an armour of 

 scale-like bones covered the rest of the body. All the 

 existing fi'ogs, newts, and such-like creatures have; however, 

 totally dispensed with the panoply of their forefathers ; and 

 have, as we all know, a soft and naked sldn. 



The true ReptUes, in which the 

 Naturalist includes crocodiles, Uzards, 

 snakes, tortoises, and turtles, as well 

 as a host of fossil extinct forms, appear, 

 speaking metaphorically, to have hcM 

 di\-ided opinions as to whether a bony 

 coat of mail was or was not a thing to be 

 retained as a permanency ; since, while 

 some extinct and early groups never had 

 anv armour, others have continued this 

 protective covering in gi'eat perfection to 

 the present day. Reptiles are, moreover, 

 remarkable for the great variety of the 

 kinds of armom' which they have dis- 

 played in the com'se of a long career. 



The Crocodiles offer the best li\-ing examples of reptiles 

 with a plate-armour, recalling that of some fishes. In 

 these fierce creatures, the back and upper surface of the 

 tail is covered with a number of oblong bony plates bmied 

 in the skin and covered by horny sliields. In the true 

 crocodiles (which in India so many people will insist on 

 misnaming alligators), this ai-mour is confined to the upper 

 surface of the body ; but in some, although not in all, aUi- 

 gators, there was also a similar armour upon the lower 

 surface. Since, moreover, most of the earlier fossil types 

 had an armour upon both aspects of the body, it seems 

 that crocodiles have, on the whole, found it advantageous 

 to get rid of the lower buckler, so that to a certain extent 

 they seem to have followed the general rule. It is, how- 

 ever, very curious to find that there were some fossil 

 crocodiles which totally discarded their armour ; and 

 have since these altogether cUsappeared, it would seem that 

 this radical change did not answer in this particular 

 instance. 



As first cousins of the crocodiles, we may briefly note, 

 then, fossil reptiles to which, fi'om the gigantic size of 

 some of them, the name of Dinosaurs, or Terrible Lizards, 

 has been apphed. Some of these huge creatures, w^hich 

 far exceeded the elephant in bulk, had a bony armour 

 which formed a solid cuirass over part of the back and 

 loins ; while in many cases the bony plates which covered 

 the body were developed into huge spikes of more than a 

 foot in length. 



The Lizards and Snakes, which we may regard as 

 advanced and liighJy specialised reptiles, having but little 

 kinship with the old-fashioned Crocodiles and Dinosaurs, 

 have, as a rule, discarded the plate-armour of the latter, 

 and have acquired instead a light scale-armour of over- 

 lapping homy scales, which are beautifully marked in 

 many of them. The snakes, indeed, never have any trace 

 of the bony plate -armout, which would, of course, interfere 

 with their hthe motions ; but in some lizards, small rudi- 

 mentary bony plates are foimd ui the skin imderhing the 

 scales, to teU the tale of their old alliance. 



Perhaps, however, the most original idea in the way of a 

 coat-of-mail is fovmd in the Tortoises and Turtles. In 

 these reptiles, the ribs and back-bone of the skeleton have 

 taken part \vith bony plates, analogous to those of the 

 crocodiles, to form a solid armour which in the land- 

 tortoises (Fig. 4) is welded together into a complete bos, 

 from which the creature can only protrude his head, tail, 

 and limbs. This remarkable and unique arrangement has 

 entailed the further curious modification that the shoulder- 



blade and haunch-bones are placed inside the ribs, instead 

 of externally to them, as in all other animals. This type 

 of armom-, which we may term box-armour, seems to have 

 been a success, since tortoises and turtles are. in certain 

 parts of the world, among the commonest of reptiles. In 

 some of those types which are dwellers in water, such as 



LaSD-TOKTOISE, SUOWlMi lUt UOMPLErB BoX-LIlvE bUELI.. 



the weU-knowu soft tortoises, or mud terrapins, so abun- 

 dant in the Nile and other tropical and subtropical rivers, 

 the breast-plate and the back-plate of the armour are, 

 however, quite separate fi'om one another, this arrange- 

 ment, probal)ly, being more conducive to freedom of action 

 in shimming. 



The great class of Bu-ds, which Professor Huxley calls 

 only highly modified reptOes, are remarkable in that there 

 is no trace of a coat-of-maU in any single species. And 

 when we come to consider the life which these creatures 

 lead, we at once see the absence of any need for such a pro- 

 tection. Thus it is quite clear that in ordinary birds, which 

 are gifted with the power of flight, a bony armour w-ould 

 not only be perfectly imnecessary as a protection but 

 would also seriously impede, if even it (Ud not totally 

 prevent, then- flight. On the other hand, in the flightless 

 birds, like the ostriches and their allies, or the kiwis of 

 New Zealand, sufiicient protection is afforded either by 

 then- size and strength, or by their nocturnal habits. 

 There are, indeed, certain flightless species, like the ex- 

 tinct dodo, of JIauritius, which have neither strength nor 

 speed, nor are of nocturnal habits. Their want of the 

 power of flight is, however, an acquked loss, due to their 

 dwelling in islands in which they are, or were, free from 

 the persecution of enemies, and thus needing no special 

 protection of any kind. 



Leaving the birds, we have to complete our brief and 

 hasty survey of the various types of armour obtaining 

 among vertebrate animals by a glance at that class which 

 includes the highest of all vertebrates, and indeed of all 

 animals. Unfortunately we are stiU in want of a good 

 popitlar name for tliis class, which includes man himself. 

 In common parlance these animals are, indeed, very 

 generally termed quadrupeds. But tliis name is objec- 

 tionable, in that it is equally apphcable to many reptiles, 

 and also since it can scarcely be applied to whales, which, 

 as is well known, belong to the same class as man. The 

 term Mammals is, however, becoming somewhat popu- 

 larised in the sense of the older term quadrupeds, and, 

 since it is in every way an excellent one, we shall make no 

 apology for its use. Now, with the exception of one 

 peculiar group or order, all mammals agree with birds in 

 being conspicuous for the absence -of a bony bodily 

 armour ; and since they have not the peculiar means of 

 protection possessed by so many of the latter class, they 

 afl'ord striking examples of om- thesis that as animals have 

 progressed in organization they have discarded protection 

 by plates of bone, to find a better one in the strength or 



