110 THE MADREPORE. 



pieces of rock, and all displayed their beautiful struc- 

 ture without any reserve. 



Just eight weeks have now elapsed since I took the 

 specimens above-mentioned ; and I have added two 

 more which I found at Hele, adhering to the perpen- 

 dicular side of a narrow, but deep rock-basin. They 

 are all alive and in excellent condition, with the ex- 

 ception of one or two that I selected to experiment 

 on. I shall proceed to describe these interesting and 

 beautiful pets. 



Doubtless you are familiar with the stony skeleton 

 of our Madrepore, as it appears in museums. It con- 

 sists of a number of thin calcareous plates standing 

 up edgewise, and arranged in a radiating manner 

 around a hollow centre. The upper edges of these 

 plates are rounded in their outline, and are free, that 

 is, not in contact with each other ; but a little below 

 the outer margin, their individuality is lost by the 

 deposition of rough calcareous matter, mingled and 

 overlaid with dirty floccose extraneous substances ; so 

 that only the general form is discernible on the out- 

 side, except at the very summit. This general form 

 is more or less cylindrical, commonly however a little, 

 and sometimes considerably wider at the top than just 

 above the bottom. The base itself is a flat expansion, 

 or rather a low cone, of which the breadth varies 

 greatlv in different specimens. 



The plates are not all of the same size. There are 

 L-ommonly about fifteen principal ones, which are 

 higher than the rest, and project more into the cen- 

 tral cavity. Between each of these and the next, are 



