312 Mr. H. J. Carter on the Stromatoporidae. 



upon Favosites gotlilandicus ; nor was I convinced to the con- 

 trary until I found a similar differentiation in MiUejJora 

 alcicormSj as already stated, viz. in the " axial structure." 



Lastly, if we go to the surface of the nodule or cone, we 

 shall find it to present the same curvilinear-Jibred coenen- 

 chyma with the separated tubes and rods as above described ; 

 but instead of a longitudinal view of them we have here only 

 their ends, in which the former often present a white opacity 

 in the centre as if some of the tahulce had possessed a styloid 

 point similar to that seen on some of the tahulce in Millepora 

 alcicornis (at all events there was something of the kind 

 here) ; while the rods present a transparent centre within the 

 opaque white calcite externally, corresponding to what was 

 seen in the longitudinal section of this part of the coenenchyma 

 in the horizontal section of the base. But the most remark- 

 able feature of the surface is the presence of more or less 

 stelliform groups of lapidified vessels or spaces irregularly 

 scattered over the laminre horizontally, and therefore repeated 

 after this fashion throughout the mass. The rays of these 

 stelliform groups are more or less dendritic in their form, being 

 branched and subdivided repeatedly, until their ultimate divi- 

 sions are lost in the vermicular spaces of the coenenchyma, 

 now equally lapidified, thus becoming continuous with the 

 branches of the neighbouring groups. It is desirable to re- 

 member this feature, as we shall hereafter find it to be repeated 

 in Stromatojwraj sometimes as mere spaces, sometimes as 

 calcified tubes. 



In some species of Caunopora the curvilinear fibre, always 

 more or less granular, appears to be cribriform ; but if origi- 

 nally composed of an aggregation of minute spicules, as in 

 Millejyora alcicornis, this appearance is easily explicable. It 

 is, however, not confined to Caunopora ; for the curvilinear fibre 

 of other coralla (ex gr. Batter shy a iruequalis) presents the same 

 kind of appearance under similar circumstances — that is, when 

 the plane of section has so passed through it as to show its 

 interior ; otherwise, as by looking at the fibre helow the sur- 

 face of the section, we may observe that the lamina which has 

 enclosed the spicules to form the fibre presents nothing of the 

 kind or merely a granulated exterior. 



Thus the presence of spicules in the fibre of Stellispongia 

 variahilis ('Annals,' 1878, vol. i. pi. xvii. fig. 10), seen in a 

 microscopic preparation kindly sent me by Dr. G. Steinman, 

 further strengthens me in my opinion that it also was a Hydro- 

 zoic coral, at the same time that it points out how easily such 

 fossil structure might be confounded with that of sponges. 

 One should always remember that Nature is ever imitating 



