426 



Reptiles. 

 Siren, 



Slow-worm, 

 Snake, 

 Toad, 

 Tortoise, 

 Turtle. 



Bone. — The structure of the osseous skeleton of animals 

 can only be satisfactorily examined by thin sections, made in 

 different directions, and ground down, pohshed, and mounted, 

 according to the directions given at page 328 ; if, however, it 

 be merely required to view the shape of the bone cells in 

 fossil bones, small thin chippings, mounted in balsam, will 

 suffice. In order to obtain a good general idea of the struc- 

 ture of bone in the vertebrate classes, specimens, cut hori- 

 zontally and vertically, should be obtained from the following 

 animals : — 



Specimens may be taken from the crania of small animals 

 so thin, that they will require no grinding at aU ; these may 

 either be mounted dry or in fluid; 



even in larger animals 



