134 BRITISH STROMATOPOROIDS. 



as regards minute structure. It is, however, readily separated by the fact that the 

 laminae are not flexuous, and that it is devoid of the astrorhizal cylinders and 

 corresponding conical " mamelons," which are so characteristic of the latter 

 species. From its next nearest ally, viz. A. hebbomense, Nich. (Stromatopora 

 astroites, Barg.), the present species is distinguished by its much stouter pillars 

 and generally coarser structure, and also by the fact that the latter possesses very 

 well-developed astrorhizge arranged in vertical groups. From A. bifarium, Nich., 

 again, it is separated by the fact that the pillars are approximately uniform in size, 

 and are not divisible into two distinct sets, as they are in the latter. None of the 

 other species of Actinostroma are sufficiently near to A. clathratum in structure to 

 require special mention in this connection. 



It is probable that this abundant species has been often described, as Stroma- 

 topora concentrica, or under some other title, by previous observers. In this case, 

 however, as in the case of many other species, it is difficult to give an extensive 

 synonymy, as most of the older descriptions and figures of Stromatoporoids are 

 insufficient to allow of confident identification. Even in the case of the Stromato- 

 pora concentrica of M'Coy, which I have placed, with some doubt, in the list of 

 synonyms of this species, it would not be possible to arrive at complete certainty 

 without an examination of the actual specimens which this observer had before him. 



Distribution. — Actinostroma clathratum, so far as known to me, is exclusively 

 confined to the Middle and Upper Devonian Rocks. In Devonshire it occurs 

 abundantly (Dartington, Teignmouth, Plymouth). In the German Devonians it 

 is very abundant in the Eifel (Gerolstein, Sotenich, &c). It is also very common 

 in the Paffrath district in certain localities (Hebborn), but is rare at others 

 (Biichel). I have not hitherto recognised this species as occurring in the Devonian 

 deposits of North America. 



2. Actinostroma vebrucosum, Qoldfuss sp. PL XVI, figs, 1 — 8, 



Ceriopora verrucosa, Goldfuss. Petref. Germ., p. 33, Taf'. x, fig. G, 1826. 

 ? Alcyonium echinatum, Steininger. Mem. de la Soc. Geol. de France, torn, i, pi. 



xx, fig. 11, 1834 

 Steomatopoua polymorpiia, jyOrbhjny (pars). Prodr. de Paleont., torn, i, p. 109, 



1850. 

 — verrucosa, Quenstedt. Petrefaktenkunde Deutscldands, Bd. v, p. 



560, Taf. cxli, fig. 10, 1878. 

 — Bargatzky. Die Strom, des. rlieiuischcn Devons, p. 



55, 1881. 

 ActIiVOSthoma vekrucosum, Nich. Ann. Nat. Hist., ser. 5, vol. xvii, p. 228, 1886. 



