PARALLELOPORA GOLDFUSSII. 



195 



figs. 5 and 7 ; and woodcut, Fig. 25) show that the skeleton-fibre is penetrated by 

 clear round spaces or pores similar to those seen in tangential sections, while 

 irregular branching canaliculi appear to be also present. The information 



Fig. 24. 



Fig. 25. 





■W- 



Fig. 24. — Part of a tangential section of a specimen of 

 Parallelopora Ooldfussii, Barg., from the Middle 

 Devonian of Steinbreche (Paffratk district), en- 

 larged 50 times. 



' 



Fig. 25. — Part of a vertical section of the preceding 

 specimen of Parallelopora Ooldfussii, similarly 

 enlarged. 



derivable from both sets of sections would thus lead to the belief that the skeleton- 

 fibre of P. Goldfussii is traversed by minute and irregular canals, together with 

 moderately numerous vesicular cavities of comparatively large size. If this view 

 be correct, then the structure of the skeleton-fibre in Parallelopora Goldfussii differs 

 from that seen in Stromatopora or Siromatoporella in degree rather than in kind. 



In certain states of preservation, however, the skeleton-fibre of P. Goldfussii 

 presents appearances differing considerably from those described above. The 

 skeleton-fibre, namely, often appears in tangential sections as if it were composed 

 of nearly transparent calcite, in which are developed dark granular tracts which 

 inosculate with one another to form an irregular open network or a close reticu- 

 lation (Plate XI, fig. 7, 1 and Plate XXV, fig. 6). In vertical sections (Plate XXV, 

 fig. 7) the fibre may show appearances very similar to those seen in tangential 

 sections ; or the dark tracts in the fibre may assume more or less of a ladder-like 

 or trellis-like arrangement (Plate XI, fig. 8). In Parallelopora capitata, Goldf. 

 sp., the appearances presented by the skeleton-fibre in thin sections are very 

 similar to those shown by P. Goldfussii, Barg. ; and in P. dartiugtonensis, Cart, 

 sp., there are indications that the fibre is similarly constituted, though none of my 



1 This figure (as also fig. 8 of the same plate) is doubtfully referred in the explanation of the 

 plate to Parallelopora (Idiostroma /) capitata, Goldf., but it really belongs to the species here under 

 consideration. 



