imperfectly -hnown Species of Stromatoporoids. 19 



satisfactorily established. In the meantime, however, I am 

 disposed to think that these two forms are congeneric, and 

 that the structure of the genus Dictyostroma, Nich., will 

 therefore prove to be that which I have here described as 

 characterizing Lahechia ? Sckmidtit. 



In any case, even supposing that the present type were 

 left in the genus Labechia, it would still be clearly separated 

 as a species from L. conferta, Lonsd. Thus, apart from the 

 presumed want of continuous radial pillars and interstitial 

 vesicular tissue, the surface-tubercles of L. ? Schmidtii are 

 much more prominent and much larger than they are in L. 

 conferta J Lonsd., and they rarely, or never to any extent, 

 coalesce, as they so commonly do in the latter. Again, I 

 have never observed in L. conferta any trace of the singular 

 surface-pellicle which so commonly spreads over the last- 

 formed layer of tubercles in the Russian form. I have there- 

 fore no difficulty in agreeing with Dybowski as to the specific 

 distinctness of the latter, and I have named it after Magister 

 Friedrich Schmidt, by whom it was originally discovered in 

 the Silurian rocks of OeseL 



Formation and Locality. Common in the Silurian formation 

 (Upper Oesel beds) of Hoheneichen, Oesel. I have also 

 found it at Kattri-pank and at Lode, near Arensburg. 



Eosenella dentata, Rosen, sp. (PI. I. figs. 4 and 5.) 

 Stromatopora dentata, Rosen, Ueber die Natur der Stromatoporen, 



p. 75, pi. X. tigs, l-ii (1867). 

 Labechia dentata, Ferd. Eoemer, Lethoea Palseozoica, p. 543 (1883). 



Ccenosteum massive ; surface unknown. The skeleton is 

 composed of undulating concentric laminas, which unite to 

 form elongated vesicles, the convexities of which point up- 

 wards. The radial pillars are rudimentary and are repre- 

 sented only by close set conical tubercles, which cover the 

 upper convex surface of the vesicles, very rarely reaching the 

 under surface of the lamina next above. The laminae are not 

 specially thickened and are mostly placed at intervals of | to 

 i millim. apart, the vesicles generally being from 1 to 2 

 millim. in greatest length. Here and there, however, are 

 found irregular spaces, often apparently periodically produced, 

 in which the vesicles are of considerably larger size, and the 

 laminae therefore further apart. 



0^.9. This species is a characteristic example of the genus 

 Rosenella, Nich.*. Vertical sections exhibit the elongated 

 * The genus Rosenella was founded by me (Men. Brit. Stromatopo- 

 roids, p. 84r, 1885) for forms which differ from Labechia in the fact that 

 the radial pillars are reduced to tubercles, covering the upper surfaces of 

 comparatively large lenticular vesicles. 



