51 



the making out of such specific peculiarities as the reticulated surface 

 of the sides of the stars. 



Madrepora flexuosa is composed of striated, cylindrical, ramifying 

 tubes, bending inwards, and then uniting : the stars being concave 

 with lamellae of similar lengths. In Ellis and Solander's Natural His- 

 tory of Zoophytes, Plate XXXI. Fig. 5 and 6, is a very correct figure 

 of the recent coral, which very much resembles a beautiful fossil spe- 

 cimen, apparently of this species of coral obtained from Sweden. It 

 is imbedded in a blue indurated marl ; which, although possessing a 

 considerable degree of hardness, has been partly removed by a careful 

 employment of some instrument ; by which the characteristic form 

 and surface of the coral is fully displayed. The terminations, as has 

 been already observed is frequently the case with the fossil corals, are 

 not preserved. The coral is however thoroughly impregnated with a 

 spathose substance, which on being polished shews the agreement of 

 the stars with those of the recent coral, in being formed of lamellae 

 all of similar lengths, reaching from the circumference to the centre. 



A fossil coral is frequently found in pretty large nodules, in St. 

 Vincent's rock, near Bristol, a small specimen of which is depicted, 

 Plate VI. Fig. 8, whose general external form approaches very nearly 

 to that of the madrepora flexuosa. Its branches, like those of the m. 

 flexnosa, are cylindrical, rough, and striated ; but its stars, instead of 

 being concave, are of a subglobose form : instead of being composed of 

 radii of equal lengths, they are formed by a certain number of rays, which 

 pass from the circumference to the centre, and by a similar number 

 interposed between the former, and which are so short as not to reach 

 above a fourth part of the length of the former. The number of these 

 rays varies from twelve to upwards of thirty of each series, according 

 to the size of the coral. These rays are intersected by perpendicular 

 concentric circular lamellae, which vary in number from two to six and 

 more, according to the growth of the coral. A red ferruginous bole 

 not only adheres to and deeply colours the external parts of these 



