76 



BRITISH STROMATOPOROIDS. 



identified as Stromatopora concentrica, Goldf., I shall name A. clathratum. It is 

 an abundant form in the Devonian formation of both Britain and Germany, but I 

 have not recognised its existence hitherto in the Devonian of North America. In 

 the Devonian formation there occur several other types, more or less closely related 



Fig. 10. 



C D 1 



Fig. 10. — Minute structure of Aetinostroma intertextum, n. sp., from the Wenlock 

 Limestone, Benthall Edge. A and B. Tangential and vertical sections, enlarged 

 twelve times. C and D. Parts of the same, enlarged twenty-four times. 



to A. clathratum. One of these is the form to which Goldf uss gave the name of 

 Ceriopora verrucosa, and which will now stand, therefore, as Aetinostroma verrucosum. 

 Another is the common Devonian species which Bargatzky described under the 

 name of Stromatopora astro'ites, Rosen ; the latter being really a true Stromato- 

 pora. I shall describe this later as Aetinostroma stellulatum. A third form, which, 

 like the preceding, is found in the Devonian deposits of both Britain and Germany, 

 is remarkable for the possession of two distinct series of radial pillars, one of large 

 size and the other small ; and I shall name this Aetinostroma bifarium. The only 

 Silurian species of the genus with which I am at present acquainted are the 

 singular A. {Stromatopora) Schmidtii, Rosen, and a new form (A. intertextum, 

 Fig. 10) from the Wenlock Limestone of Britain. 



The essential character which distinguishes Aetinostroma from the genus 

 Clathrodictyon is the continuity of the radial pillars in the former. As no vertical 

 section can possibly be prepared, which shall run precisely along the axis of any 

 single radial pillar, or of any set of pillars, throughout its entire length, it is not pos- 

 sible to ascertain precisely the extent to which this continuity of the radial pillars 

 is carried. A single radial pillar may often be followed through ten, fifteen, 

 twenty, or more laminae and successive interlaminar spaces ; and I am of opinion 



