﻿PARALLELOPORA GOLDFUSSII. 193 



generally intersected by calcareous partitions or " astrorhizal tabula3 " (Plate XXV, 

 fig. 4). In vertical sections the cut ends of these large astrorhizal canals (when 

 these structures are present) appear as round or oval apertures of considerable 

 size. Apart from these, however, some specimens show numerous irregular, oval 

 or rounded cavities of considerable proportionate dimensions, which appear to be 

 generally in connection with the astrorhizal canals, though this cannot always be 

 demonstrated. Such cavities are commonly crossed by calcareous partitions, and 

 are entirely wanting in some specimens. They are more largely developed in the 

 allied P. capitata, Goldf. sp., than in the present form, and may perhaps be 

 compared with the " ampullas " of the existing Hydrocorallines. Leaving out of 

 sight the minute structure of the skeleton-fibre itself, the coenosteal tissue of 

 Parallelopora Goldfussii is built upon the same general plan as that of Stromatopora 

 proper. The skeleton-fibre presents, however, very remarkable microscopic 

 characters, and it may be as well here to treat of these in some detail, as regards 

 not only the present species but also its immediate allies, since upon this alone 

 depends any distinction which can be drawn between Parallelopora, Barg., and 

 Stromatopora, Goldf. 



The type-species of Bargatzky's genus Parallelopora is P. ostiolata, Barg., of 

 the Middle Devonian of Germany, a form which has not hitherto been recognised 

 in Britain, and which does not, therefore, fall to be described here. Only a single 

 imperfect specimen of this remarkable type is at present known, and, by the kind- 

 ness of Prof. Schluter, I have been enabled to examine this both macroscopically 

 and by means of thin sections. As previously pointed out (Introduction, p. 95), 

 the coenosteal tissue of P. ostiolata, Barg., is completely reticulate, and is 

 traversed by numerous tabulate zooidal tubes (Plate II, figs. 6 and 7), the general 

 structure thus entirely agreeing with that of Stromatopora proper. The skeleton- 

 fibre is, however, peculiar in being traversed by numerous dark, rod-like bodies of 

 very minute size, which have a general direction parallel to the radial pillars, or, 

 in other words, at right angles to the surface. As seen in tangential sections 

 (Plate II, fig. 6; and woodcut, Fig. 23, a), these rods appear as rounded or oval 

 black dots, scattered throughout the fibre, but most abundant round the margins 

 of the zooidal tubes. In vertical sections (Plate II, fig. 7 ; and woodcut, 

 Fig. 23, b) the rods in question are seen as dark-coloured vertical lines, connected 

 at intervals by similarly dark-coloured transverse beams, thus giving to the fibre 

 the appearance of a trellis-like tissue. Bargatzky (op. cit. supra, p. 51, figs. 10 

 and 11) interpreted the appearance just described as indicating that the coenosteum 

 of P. ostiolata was composed of numerous interstitial tabulate tubes of minute 

 size, surrounding and isolating a series of larger tabulate tubes, the structure 

 being thus comparable with that seen in some Monticuliporoids (as in Gallopora), 

 or in Heliolites. Bargatzky's figures, however, are ideal, and no traces of the 



