46 



Transactions of the Society. 



one and of any suitable material, with an opening through which 

 one object and its label only can be seen. 



Fig. 7 represents the upper view of the whole of the arrange- 

 ment, the cover-disk hinged to the top of the supporting frame and 



Fig. 7. 



held down flat by spring clips to its other extremities. These clips 

 tui'n to the right when it is desired to raise and throw back the 

 hinged cover for the purpose of changing the object-disks on the 

 central pivot, but are prevented by a stop-pin from slipping or 

 moving to the left when the disk is moved (in direct rotation) to 

 bring successive objects into the field. 



Suitable objects for presenting thus will readily suggest them- 

 selves, say for example, sections of exogens, endogens, and acrogens ; 

 growth and development of various forms of animal and vegetable 

 life, and comparison of all kinds of fossil organic remains with the 

 allied forms of the present day. 



