188 NATURE'S TEACHINGS. 



I have among my microscopic objects a piece of wing from 

 a South American butterfly, the scales of which are oblong and 

 bent, just like the curved tiles shown in the second right-hand 

 figure of the illustration. These beautiful scales are deep 

 azure or warm brown, according to the direction of the 

 light. 



Perhaps my readers may call to mind that some architects 

 dislike the flat, square form in which slates are usually put 

 on roofs, and try to make them less formal. 



Sometimes they take their square slates, and fit them with 

 one of the angles uppermost, so that each slate looks something 

 like the ace of diamonds in a pack of cards. Sometimes they 

 are still more ambitious, and certainly succeed in producing a 



SHELL OF TORTOISE. HEXAGONALLY TILED ROOF. 



better effect, by cutting the slates in hexagons instead of 

 squares, and fixing them as shown in the right-hand figure of 

 the illustration. Putting aside the familiar hexagons of the 

 honeycomb, and the apparent hexagons of an insect's com- 

 pound eye, we have in the common Tortoise an example of 

 hexagonal plates that exactly resembles the slate roofing. 



In the next illustration we have a variety of the same prin- 

 ciple exhibited in differently shaped tiles and scales. The 

 figures on the right hand show the pointed, the square, and the 

 oblong tiles. These also would answer very well as representa- 

 tions of different forms of scale armour, the one being intended 

 to throw off rain, and the other to repel weapons. 



On the other side of the illustration are examples taken from 

 the animal kingdom. First comes the Bajjerkeit, or Short- 

 tailed Manis, which has already been mentioned, and whose 

 imbricated scales will resist the blows of any spear or sword. 

 As to my own specimen, when it is struck, it resounds as if it 

 were a solid plate of metal, and I should think that during the 



