Mr. H. J. Carter on the Stromatoporidje. 315 



which is represented by the horizontal lines of the former, and 

 the vertical rods (which are represented by their ends only in 

 the latter) , respectively, while, where the plane of the horizon- 

 tal section passes between two laminae, the points of the rods 

 ahne are seen on the immediate surface, it becomes evident 

 that the coenenchyraa is formed of vertical rods which support, 

 at variable distances, the horizontal cribriform laminje. 



Again, it is evident that the coenosarc of this coenenchyma 

 in Stromatojjora was as contiimous throug-hout as in that of 

 Caunopora, and that the continuity through the cribriform la- 

 minaa was kept up in the same way as through the cribriform 

 transverse septa of Tubipora musica. 



Further, it may be observed that the white or opaque " rods " 

 of calcite, as well as the rectilinear structure of the laminae ge- 

 nerally, present a more or less transparent calcite internally, 

 as in the " axial structure " of Millepora alcicornis and in the 

 rods of Caunopora, before noticed, whereby, if this had not 

 already been explained, it might seem as if they were origi- 

 nally hollow or tilled with some soft fleshy matter. 



Lastly, in the horizontal section may be seen, as in Cauno- 

 fora, the stelliform groups of vessels more or less scattered 

 over each lamina, together with more or less transverse sections 

 of them, according to their position, in the vertical section of 

 Stromatopora — sometimes in distinct lines where the vessels 

 have calcareous walls, at others as mere spaces in the recti- 

 linear structure, when they may be so indistinct as to escape 

 observation if not sought for carefully ; while at other times 

 they may not be present all, as stated in Millepora alcicornis, 

 on account of their being concealed underneath the plane of 

 the section, which may have just taken away the upper part 

 of the layer bearing them, and not sufficient of the lower part 

 to expose the following set. Again, in the vertical section 

 there is often indication that a continuous vertical canal, to 

 which I have before alluded, passed up through the whole of 

 the stellate groups in that line, and, thus connecting them 

 together, may have been developed from calicles successively 

 formed on the surface, whereby a continuous canal would 

 be kept up, as in the branch of Madrepora ahrotanoides before 

 cited ; or the canal may be interrupted ; or there may be no 

 defined centre or indication of opening there as in Stromatopora 

 astroites, Kos. {op. cit. Taf. ii. fig. 7) ; or there may be no stel- 

 late centre and the form may be merely dendritic, as in S. 

 Sclimidtii, E.OS. {ib. Taf. iv.fig. 1), finally passing into thestrag- 

 gling form observed in Millepora alcicornis. Further, the 

 branches of the stellate group may not be horizontal, but sloj)ing 

 all round, as when it is successively developed on the summit of a 



