10 ANIMAL LIFE PAST AND PRESENT. 



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 spines of more than a 

 foot in length ; and in others the back and tail were 

 armed with a row of large plates set edge- ways along 

 the back-bone, and extending from the head to the tip 

 of the tail, as shown in Fig. 39. 



The Lizards and Snakes, which we may regard as 

 advanced and highly 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 acquired instead a light scale-armour 

 of overlapping horny scales, which in many of them 

 are beautifully marked. The snakes, indeed, never 

 have any trace of the bony plate-armour, which would, 

 of course, interfere with their lithe motions; but in 

 some lizards, small rudimentary bony plates are found 

 in the skin underlying the scales, to tell the tale of 

 their old alliance. 



Perhaps, however, the most original idea in the way 

 of a coat-of-mail is found in the Tortoises and Turtles.* 

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

 have taken part with 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 com- 

 plete box, from which the creature can only protrude 

 its head, tail, and limbs. This remarkable and unique 

 arrangement has entailed the further curious modifica- 

 tion that the shoulder-blade and haunch-bones are 



* See Chapter VII. 



