92 MOSS CORALS. 



Some idea of the minuteness of various species 

 of these fossil moss corals may be formed, when it is 

 known that in the finest levigated whiting, multi- 

 tudes are present, without having suffered change in 

 the preparation of the chalk ; and that, by the aid of 

 the microscope, a mosaic work of moss corals may 

 be seen, of varied and beautiful forms, on the chalk 

 coating upon the walls of a room. 



The best way of observing these minute fossils is, 

 to place a drop of water on a delicate film of mica, 

 and add to it as much of fine chalk powder as 

 the top of a penknife will take up. Let this be 

 spread out like a very thin layer, the water be drained 

 off, and with it the floating particles. When the 

 layer is quite dry, it should be coated over with 

 pure Canada balsam, holding it during the addition 

 of the balsam over a spirit lamp till it becomes 

 slightly fluid ; but clear and without froth. In the 

 management of this, some dexterity and practice are 

 requisite ; but when effected with delicacy, the 

 preparation generally proves successful. 



Some of the moss corals appear as a cluster of 

 minute cells, or open vesicles, of a calcareous struc- 

 ture, forming patches of greater or less extent, on 

 all marine productions, vegetable, animal, or inor- 

 ganic. Their minuteness often causes them to be 

 overlooked by the ordinary eye, nor is their true 

 character to be discovered except by microscopic 

 examination, when they are seen distinctly as 

 clusters or groups of cells. Each of the cells is 



