90 BRITISH STROMATOPOROIDS. 



of its numerous peculiarities, it would not be expedient to regard Beatricea as the 

 type of a special family. 



Fam. 3. Steomatoporidj;, Nich. 



Ccenosteum massive, laminar, dendroid, or encrusting, often with a basal 

 epitheca. Radial pillars usually more or less extensively combined with their 

 horizontal connecting-processes, so as to give rise to a continuously reticulated 

 skeleton. The skeleton-fibre is thick, and is minutely porous or tubulated. 

 Definite zooidal tubes, crossed by well-developed " tabulae " are present ; but the 

 coenosteum is not traversed by a tabulate axial tube. 



I include in this family the two principal genera Stromatopora, Goldf., as here 

 emended, and Stromatoporella, gen. nov. The forms which have been referred by 

 Bargatzky to Parallelopora and by myself to Syringostroma also belong to the 

 family, but it is questionable if these names can be regarded as of more than 

 subgeneric value. Moreover, most of the forms which have been referred to the 

 genera Caunopora, Phill., and Diapora, Barg., are essentially referable to this family, 

 but as the true nature of these so-called genera is a matter of great intricacy, I 

 shall discuss it separately later on. 



In the typical members of this family, namely in the species of Stromatopora 

 itself, the skeleton is a completely reticulated one, and the radial pillars can hardly 

 be said, as a rule, to have any existence as distinct structural elements. In the 

 vermiculate structure of the skeleton, and in the presence of definite tabulate 

 zooidal tubes, the typical Stromatoporce make a decided approach to the recent 

 genus Millepora, Lam. In fact, the most striking points in which they differ from 

 the latter are that they do not appear usually to have possessed more than a single 

 series of zooidal tubes, while the general skeleton-fibre has a peculiar and charac- 

 teristic microscopic structure (Plate I, figs. 3 — 7, and Plate XI, figs. 1 — 4). There 

 are, however, good reasons, apart from mere general likenesses in form and mode of 

 growth, for not removing the Stromatoporidce far from the Actinostromidce. Thus, 

 though there are wide differences between a typical Stromatopora and a typical 

 Actino stroma, nevertheless the groups which these respectively represent are closely 

 linked together by various transitional forms. In the vesicular coenosteum of 

 Clatlirodictyon we have an approximation to the reticulate skeleton of the Stroma- 

 toporido3 ; while in the genus Stromatoporella the radial pillars are so far distinct 

 that vertical sections have a general resemblance to those of Actinostroma itself. 

 Again, in Stromatopora Beuthii, Barg. (Plate V, figs. 12 and 13), the radial pillars, 

 which are so characteristic of the Actinostromidce, are more or less obviously 



