GENUS STACIIYODES. 107 



developed in the former than in the latter. Moreover, the tabulate zooidal tubes 

 of Idiostroma have only a very feeble representation in II 'ermato stroma, while the 

 axial tabulate tube of the typical forms of Idiostroma, with its lateral tabulate 

 offshoots, is a feature apparently unknown in the present genus. 



Genus Stachyodes, BargatzJcy. 

 (' Zeitschr. der deutschen G-eol. Ges.,' Jahrg., 1881, p. 688.) 



Coenosteum having typically the form of branched cylindrical stems, which are 

 rooted basally, and terminate distally in rounded ends. The skeletal tissue is 

 of the reticulated type, neither the radial pillars nor the concentric laminae being 

 developed as distinct structures. The skeleton- fibre is minutely tubulated, the 

 tubuli running parallel with the zooidal tubes. Definite zooidal tubes, which are 

 sparingly tabulate, are present and open on the surface by rounded apertures. In 

 the centre of the stems is a large axial tube, which is crossed by numerous curved 

 or straight tabula?, and which gives off diverging lateral branches, which are also 

 tabulate. No astrorhizas appear to be present. 



It seems probable that one of the forms which Groldfuss included under the 

 name of Stromatopora polymorpha, namely, the form which Bargatzky named 8. 

 polyostiolata, is really a Stachyodes, as shown by the minute structure of the 

 skeleton of the original specimen. The above definition, however, is based upon 

 the singular type which Bargatzky (loc. cit. supra) has described under the name 

 of Stachyodes ramosa. Having examined a large series of specimens of this, which 

 I have obtained from the Devonian Rocks of Devonshire and of Germany, I see 

 no reason to doubt that it is really the previously described Stromatopora (Cauno- 

 pora) verticillata, M'Coy (' Brit. Pal. Foss.,' p. 66,) under which specific title it 

 will therefore have to remain. The coenosteum in this form consists of cylindrical 

 stems, generally about a centimetre in diameter, which commonly branch, and 

 which terminate in rounded ends (Plate VIII, fig. 9). In its general aspect the 

 fossil closely resembles the dendroid species of Pachypora, Lindst., a resemblance 

 which is increased by the fact that the surface is extensively covered with the 

 rounded apertures of the zooidal tubes. Parts of the surface, however, very com- 

 monly do not exhibit these apertures, but, on the contrary, are occupied by a thin 

 investing calcareous membrane (Plate VIII, fig. 12). Judging from the analogy 

 of Amphipora ramosa, it is not improbable that the development of this membrane 

 is connected with the production of reproductive zooids in " ampulla?." Though 

 the dendroid form is the commonest, I have seen examples which ■ form irregular 

 masses. In the centre of the stem runs a principal axial tube (Plate VIII, figs. 



