n 



polype. In the centre of this part of the specimen, the base of the 

 root may be observed ; the root itself, with its surrounding processes, 

 having been bowldered down nearly smooth. 



Plate IV. Fig. 1, represents a. variety of this species, which has 

 acquired more of a pyramidal form ; its body having been so elongated 

 as to have terminated almost in a point, where the root has evidently 

 been broken off. The remains of the root are however still observable, 

 and are surrounded with several processes, the appearance of which 

 sufficiently evince that their office was to assist in affixing the plant' 

 like habitation of the animal to its destined spat. 



A circumstance which particularly claims observation in this species 

 of madreporite, is, that of a second coral proceeding, in the manner of 

 proliferous flowers, from the disk of the first. In the specimen, Plate 

 IV. Fig. 3, a separation may be seen of about half the circumference 

 and nearly of half the diameter of the coral. The commencement of 

 a similar process is observable in several other specimens. The speci- 

 men, Fig. 5, has obviously obtained its increase in this manner, by 

 the formation of fresh corals from the disks of the preceding. 



The size of these corals, as has been already observed, vary con- 

 siderably : indeed, I suspect that I have seen some from Derbyshire, 

 even upwards of a foot in length. Equally considerable also is the 

 variety of forms which they assume. In some the shape is completely 

 turbinated: in others the length is considerably protrac ed ; some- 

 times in a straight, and at other times in a curved direction, as at 

 Plate IV. Fig. 8. The polished longitudinal section of this fossil 

 shews the internal part of the madrepore to have been divided by 

 transverse lamellae, which correspond with the circular projections on 

 the surface. Such of these fossils as possess a curved form are fre- 

 quently of a considerable size, sometimes nearly approaching even to 

 the magnitude of a bullock's horn. In a specimen from Perthshire, 

 lately offered to me for examination, not only the form of the goat's 

 or ram's horn, but the colour, and even somewhat of the disposition 



