344 Mr. H. J. Carter on Stromatopora dartingtoniensis. 



independent evidence was of course more acceptable than if I 

 had selected the specimens myself. I afterwards found, on 

 polishing another specimen of a species of Stromatopora with 

 curvilinear structure, that I had brought away from "Pit-Park 

 Quarry " a much better illustration of it than in any other of 

 a like kind. 



Here it is necessary to state that, in all probability, the 

 finding of a specimen of Stromatopora, in which the calcspar 

 usually filling the branches of the astrorhiza has been re- 

 moved by decomposition, and the tabula? left, is very rare, 

 and that, even when it is found, the branches for the most 

 part, not running along on the same plane, may only be par- 

 tially exposed here and there in the horizontal section, so as 

 to present but a few of the tabula? with which they may be 

 more or less traversed throughout. Then the irregular dis- 

 position of tabula?, both as to distance and direction, is rather 

 the rule than the exception, as may be seen by the illustra- 

 tions of the "Tabulate Corals" at the end of Prof. Nicholson's 

 magnificent book, to which I have before alluded ; while the 

 impossibility of distinguishing the tabula? from the general 

 mass of transparent calcspar with which the branches of the 

 astrorhiza are usually filled, is illustrated by a similar occur- 

 rence sometimes even in Favosites, where they are generally 

 so well marked. 



When, however, we recur to the slices of more consolidated 

 Stromatoporce which are polished over the lamination, this 

 tabulated structure in the branches of the astrorhiza is not 

 so uncommon, if we know what to look for ; but as, in Mille- 

 pora, the astrorhizal venation of Stromatopora is, as it were, 

 excavated in the coenenchymal structure without wall, and the 

 vermiculate channels of the coenosarc freely open into the 

 cavity of the branch, so in the horizontal section, which barely 

 touches the branch, a number of holes may be observed along 

 its course ; but the fibre separating these must not be con- 

 founded with the tabula?, nor must the extension of the 

 coenenchymal structure or filament across the branch be con- 

 founded with them ; but we must look for a specimen in 

 which the plane of the section has fairly taken off the whole 

 of the surface of the branch, and then seek for white lines 

 which traverse it directly (that is, without curvature) and not 

 in continuation with the fibre of the coeenchyma, when there 

 will be little left for us to conclude than that such a structure 

 must be owing to tabulation. 



Although the fact may not bear directly upon the argument 

 in favour of tabulation in Stromatopora, yet it may be ob- 

 served that all the corals in the " quarry," which are more or 



