236 Dr. H. A. Xicliolsoa on some new or 



centim. The surface may be smooth or may be covered with 

 conical " mamelons," upon which the axial canals of the 

 astrorhiza3 open. Astrorhiza? are always present and are 

 remarkably large, their centres being often 2 to 3 centim. or 

 more apart. The astrorhizal canals are furnished with 

 " astrorhizal tabulse," and the astrorhizal systems are in 

 vertical groups, each group having a common axial canal. 

 The skeleton-fibre is thick and traversed by minute microscopic 

 tubuli (PL VIII. figs. 5, 6) . The radial pillars are incomplete, 

 being as a rule confined to a single interlarainar space, and 

 average about ^ millim. apart. The " concentric laminae " 

 are very distinctly developed, and are placed about as far 

 apart as the radial pillars. Definite zooidal tubes are very 

 imperfectly developed, and often do not exist at all as separate 

 structures. 



Obs. This remarkable species exhibits many interesting 

 features which cannot be here discussed. It is closely related 

 to Stromatoporella granulata*, Nich., and S. damnoniensis^ 

 Nich., the three forming a natural group of forms, which are not 

 much more than varietally distinct, though it is convenient to 

 give them separate titles. It is also nearly alHed to S. tarninata^ 

 Barg. sp., and to S. arachnoidea^ Nich. The feature which, 

 more than any other, distinguishes S. eifeliensis from all these 

 related types is the extraordinary development of the astro- 

 rhizal system. It is further distinguished from /S'. damno- 

 nietisis by the greater delicacy of its skeletal tissue ; this 

 latter species (as also S. granulata) being either destitute of 

 astrorhizje or having these structures very feebly developed. 

 From S. laminata^ Barg. sp., it is further distinguished by 

 the fact that the radial pillars are confined to their respective 

 interlaminar spaces, and there are few or no definite zooidal 

 tubes to be recognized in vertical sections ; whereas in the 

 latter species the radial pillars are often continuous through 

 several interlaminar spaces, and there are numerous tabulate 

 zooidal tubes. From ^S*. arachnoidea it is distinguished by 

 the absence or slight development of the extraordinary " inter- 

 laminar tabula " which characterize the latter. 



Formation and Locality . Abundant in the Middle Devonian 

 of the neighbourhood of Gerolstein, in the Eifel. It com- 

 monly occurs in the " Caunopora state," as well as entirely 

 without "Caunopora-tubes j" and it is often associated para- 



* Stromatoporella granulata was described by me (Ann. & Mag. Nat. 

 Hist. 1873, xii. p. 9i, pi. iv. figs. 8 and 3 rt) under the name of Stromato- 

 pora (iranulata. I f-hall give a brief diagnosis of the species later on. It 

 occurs in the Devonian rocks of Canada. 



