228 Di"- H. A. Nicholson on some new or 



" Astrorhizaj " seem to be generally wanting in German 

 examples, but are usually present, though very feebly deve- 

 loped, in British specimens. _ 



The species with which A. clathratum is most nearly allied 

 is A. verrucosum, Goldt., the differences between the two 

 being wholly as to their mode of growth. From its next 

 nearest ally viz. A. Jiehbornense, 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 astro- 

 rhizge, which are arranged in vertical groups. 



Formation and Locality. Common in the Middle Devonian 

 of Hebborn (Schladethal) and in other localities in the Paf- 

 frath district ; also very abundant in the same formation in 

 the Eifel (Gerolstein, Soteuich, &c.). Abundant in the 

 Middle Devonian of Devonshire (Dartington &c.) . 



Actinostroma verrucosum^ Goldf., sp. 



Ceriupora vernicosa, Goldf, Petref. Germ. Taf. x. fig. 6 (1826). 

 Stromatopora vernicosa, Bargatzky, Die Stromatoporen des rheinischen 

 Devons, p. 55(1881). 



Ohs. The minute structure of this species is in all essential 

 respects identical with that oi A. clathratum, Nicli. ; but the 

 ccenosteum is always developed round a series of separate 

 centres of o-rowth, round which the laminai are concentrically 

 produced. Hence the concentric laminae are regularly undu- 

 lated and the surface exhibits numerous prominent conical 

 eminences or " mamelons,^' usually of considerable size, each 

 of these representing a centre or axis of growth.^ 



Formation and Locality. Comparatively rare in the Middle 

 Devonian formation of Biichel (Paffrath district), and also in 

 the same formation in the Eifel (Sotenich, Gerolstein, &c.). 

 I have not recognized the species as yet in the Devonian form- 

 ation of Britain. 



Actinostroma Jiehbornense , Nich. 

 (PL VII. figs. 7 and 8.) 



Stromatopora astroites, Bargatzky, Die Stromatoporen des rheinischen 



Devons, p. 56 (1881). 

 [Non Stromatopora astroites, Rosen.] 



The ccenosteum in this species is massive and very regu- 

 larly laminated, the surfaces of the laminaj being smooth and 

 exhibiting numerous large astrorhizje, the centres of which are 

 usually from 6 to 8 millim. apart. The radial pillars are " con- 

 tinuous," slender, and placed at about | millim. apart, the same 



