202 BRITISH STROMATOPOROIDS. 



cavities of the coenosteum, have been filled, as previously explained (p. 31), with a 

 more or less opaque calcareous mud, while the real skeleton has been more or less 

 extensively converted into transparent calcite. A " reversed " state of preserva- 

 tion is, however, by no means peculiar to the present species, and I have noticed 

 it in Stromatojjora florigera, Nich., S. insequaUs, Nich., and occasionally in 8. con- 

 centrica, Goldf. 



I have never seen an example of 8. dartingtonensis in the " Caunopora-state," 

 though there is no reason to doubt that it occurs occasionally in this condition. 



Distribution. — Parallelopora dartingtonensis, Cart, sp., has hitherto been recog- 

 nised only in the Middle Devonian Limestones of Devonshire. The ordinary form 

 of the species is not uncommon at Pit-Park Quarry, Dartington (the original 

 locality for the species). Both the normal form of the species and the variety 

 filitexta occur not uncommonly in the Devonian pebbles of the Triassic con- 

 glomerates of South Devon. 



Germs 3. — Stkomatoporella, Nicholson, 1886. 



(General Introduction, p. 92.) 



1. Steomatoporblla granulata, Nich. PI. I, figs. 4 and 5 and 14 and 15 ; PI. IV, 



fig. 6 ; PL VII, figs. 5 and 6 ; and 

 PL XXVI, fig. 1. 



Steomatopoea gbanitlata, Nicholson. Ann. and Mag. Nat. Hist., ser. 4, vol. xii, 



p. 94, pi. iv, figs. 3, 3 a, 1873. 

 — — Ibid., ser. 5, vol. xviii, p. 10, 1886. 



The coenosteum in this species forms laminar expansions of considerable size, 

 which are not incrusting, but are attached basally by a peduncle, and have the 

 rest of the lower surface covered by a concentrically wrinkled and striated 

 epitheca. The thickness of the coenosteum varies from less than 2 mm. up to 2 

 or 3 cm. The surface (Plate XXVI, fig. 1, and Plate IV, fig. 6) shows a variable 

 number of low rounded or conical eminences or" mamelons," the apices of which 

 are usually perforated, each showing in general a single circular opening repre- 

 senting the axial canal of one of the astrorhizal systems. From the apices of the 

 mamelons radiate more or less conspicuous astrorhizal gutters, and the general 

 surface is covered with close-set tubercles of various sizes, the smaller of these 

 being imperforate, while the larger ones are pierced at their apices by distinct 

 circular apertures (Plate I, fig. 14). In places the surface-tubercles coalesce into 



