NATURAL HISTORY OF SELBORNE. 111 



water. This may be a protection for him against the assaults of 

 his enemies, though I cannot imagine that Nature anticipated 

 the discovery and use of musket balls. 



Tf we look for scales in land animals, we shall find them more 

 especially in the pangolin, the armadillo, and the tortoise. 

 The pangolin's scales are very like, but yet differ from, fish- 

 scales proper, inasmuch as they are not intended to be wetted. 

 In the armadillo we find a series of scales of peculiar shape, 

 not let into pockets as in the fish, but each connected with 

 its neighbour by soft skin, so that the armadillo's skin may 

 be said to be a series of oblong-headed nails (such as are used 

 to tack on furniture fringes) fastened into a covering whicli 

 forms the skin of the animal. The armadillo has to roll him- 

 self into a ball as occasion requires ; therefore the studs of 

 his armour are so beautifully fitted as to size and shape that he 

 can roll them up into a ball without the slightest appearance of 

 a crease or wrinkle. 



In the case of the armadillo, who lives under a covering of 

 horny, flexible skin, please to observe that his backbone, and 

 all other bones, as well as his lungs, heart, and o';her viscera, 

 are all underneath this flexible roof to his body. In the tortoise 

 we find quite another arrangement. Take a tortoise-shell and 

 boil it, and you will find that you can pick off the scales one by 

 one, and underneath the scales is a tenter-house of solid-formed 

 bone. This dome- shaped house is not composed of a con- 

 tinuous mass of bone, as a tea-cup is made of a continuous 

 plate of pottery, but rather of a series of small bones, all 

 properly arched to suit the original curve, and jointed together 

 in a most marvellous manner. It was not possible to rivet or 

 bolt these plates together. Mortar could not be used to bind 

 them together, as in the case of an arch made of bricks. What 

 then must be done ? If the reader will examine for himself, he 

 will find that the edges of each bone are deeply serrated, and 

 that the serrations fit in such a workmanlike manner one into 

 the other that an amount of solidity is gained which could not 

 have been equalled if the whole dome had been cast in a solid 

 piece. 



But how is the tortoise to live in his house ? "Where are his 

 ribs to go to ? Let us examine. In ordinary animals the back- 

 bone forms an attachment for the ribs, and there are plenty of 

 muscles, &c., cnit&ide the ribs. In the tortoise, the ribs them- 

 selves are actually used to form part of the dome or roof. By 

 examining the inside of a tortoise-shell, the fact will at once 

 become apparent. The ribs will be seen forming the girders of 

 this wonderful roof, and they are connected together by means 



