GENUS PARALLELOPORA. 95 



In addition to the forms above alluded to there are several other imperfectly 

 known Stromatoporoids which probably belong to this genus. It is tolerably 

 certain, namely, that some of the forms included by Goldfuss under the name of 

 Stromatopora polymorpha, {e. g. S. curiosa, Barg.) are really referable to Stromato- 

 porella. The Stromatopora nulliporoides, Nich., of the Devonian of North America, 

 and the allied, or identical, Coenostroma incrustans, Hall and Whitf. (Plate III, 

 fig. 6), from the same formation, are likewise probably referable here. 



Genus Parallelopora, Bargatzhy. 

 (' Die Stromatoporen des rheinischen Devons,' p. 63, 1881.) 



The general structure of the skeleton in the forms which Bargatzky placed 

 under Parallelopora resembles that of the typical Stromatopora}, the radial and 

 horizontal elements of the skeleton being so amalgamated as to give rise to a 

 continuously reticulated framework, traversed by vertical tabulate zooidal tubes. 

 The coarse, reticulated skeleton-fibre is traversed by irregular vertical tubuli, or 

 by minute dark-coloured vertical rods, which are united at intervals by horizontal 

 bars. Astrorhizse are present. 



It seems doubtful if Parallelopora, Barg., can be regarded as having the rank 

 of a genus. The general structure of such forms as I have seen (including 

 Bargatzky's original specimens) would appear to be very much the same as that 

 of Stromatopora, Goldf., or of Idiostroma, Winch., some of the described species 

 being more like the former genus, and others more like the latter. The peculiarities 

 in the structure of the forms in question are, in fact, chiefly concerned with the 

 existence in the skeleton-fibre of minute vertical tubules, in many respects similar 

 to the tubuli seen in Stachyodes, Barg. In one form, viz. P. Goldfussi, Barg., of 

 which I have examined the original specimen, the skeleton-fibre is coarsely tubulated 

 (Plate XI, fig. 9) ; but the general structure is not otherwise peculiar. I am dis- 

 posed to think this species to be really identical with Idiostroma ? {Stromatopora) 

 mpitatum, Goldf. 



More remarkable appearances are presented by P. ostiolata, Barg., from the 

 original of which, through the kindness of Prof. Schliiter, I have also prepared 

 thin sections. In tangential sections of this type, as previously mentioned, the 

 skeleton is seen to be densely reticulated, and to be traversed by numerous rounded 

 zooidal tubes (Plate II, fig. 6). The skeleton-fibre is very thick and very trans- 

 parent, so that it is in places difficult to distinguish it from the surrounding 

 calcitic matrix. It is, however, distinctly marked out by a vast number of rounded 



