GENUS AMPIIIPORA. 109 



Genus Amphipora, Schulz. 



(' Die Eifelkalkmulde von Hillesheim,' p. 89, 1883. Eeprinted from the ' Jahrb. der konigl. preuss. 



geol. Landesanatalt ' for 1882.) 



The coenosteum in this genus is in the form of slender cylindrical stems, which 

 may or may not branch in a dichotomous manner. In the centre of the coenosteum 

 and running its entire length is a wide axial tube, which is intersected by transverse 

 or funnel-shaped tabulae. The general skeletal tissue is continuously reticulated, 

 of the type of that of the Stromatoporidce, but apparently compact instead of being 

 minutely porous. Distinct but irregular zooidal tubes radiate outwards from the 

 axial tube to open on the surface by definite apertures. The surface sometimes shows 

 the apertures of the zooidal tubes, surrounded by vermiculate or tuberculated 

 margins, but at other times the cylindrical coenosteum is surrounded by a zone of 

 large-sized lenticular vesicles, which are enveloped by a delicate, apparently imper- 

 forate calcareous membrane. 



So far as known, the genus Amphipora is represented by one species only, viz. 

 the form described by Phillips under the name of Caunopora ramosa (' Fig. and 

 Descript. Pal. Foss.,' p. 19). This remarkable species occurs in vast numbers in 

 the Devonian Rocks of Germany and Devonshire, apparently occupying in the 

 former region, as probably in the latter also, a definite horizon in the upper portion 

 of the Middle Devonian series (the " Ramosa-Banke " of Schulz). In its dendroid 

 coenosteum (Plate IX, fig. 1), Amphipora ramosa, Phill., resembles Stachyodes 

 verticillata, and this resemblance is further increased by the fact that in both these 

 types the skeleton is traversed by a principal axial tabulate tube (Plate IX, figs. 2 

 and 4). The skeleton-fibre of Amphipora ramosa exhibits, however, no traces of 

 the microscopic tubulation which is so characteristic of even the smallest fragment 

 of the skeleton of Stachyodes. In fact, the skeleton-fibre of Amphipora appears to 

 be quite compact, though there are grounds for thinking that this is perhaps only 

 the result of mineralisation and that the fibre may be to some extent porous. The 

 most remarkable peculiarities of A. ramosa are, however, connected with the 

 condition of its surface. In examining a large series of specimens, one is at once 

 struck by the fact that many individuals have the surface covered with the rounded 

 apertures of the zooidal tubes, which are bounded by tuberculate margins and 

 which give to the fossil very much the appearance of a small species of Pachypora. 

 On the other hand, many other individuals (Plate IX, fig. 1) have the surface 

 entirely covered by a thin, imperforate, calcareous membrane, which gives them 

 very much the aspect of the stems of such Corals as Lithostrotion junceum or 



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