42 THALLOPHYTES, BRYINAE. 



apex, which however is seldom preserved. The central axile tube is of 

 extraordinary width, and is surrounded by numerous crowded rings or 

 whorls of lateral canals, which traverse the rind and have the passage open 

 to- the outside. A similar construction is seen in Gyroporella vesiculifera l 

 (Fig. 4 C-E\ which belongs to the main dolomite of the Upper Keuper and 

 occurs chiefly and abundantly in the Alps of Lombardy ; but here the lateral 

 canals, forming less distinct rings, are closed on the outer side by a small 

 and somewhat convex plate. We can scarcely be wrong in assuming that 

 this difference arose in a construction originally alike in both cases, in 

 consequence of the apical membrane of the branch being sometimes calcified 

 and sometimes remaining unaltered. There is therefore an essential differ- 

 ence between the Tertiary forms first considered and these forms from the 

 Trias ; the latter, in place of complicated lateral branch-systems producing 

 sporangia, have only whorls of short simple members, which are either 

 cylindrical or somewhat swollen and enlarged. Whether these members 

 developed directly into sporangia by formation of septa between them and 

 the lumen of the main axis, or in certain circumstances produced at their 

 extremity free sporangia which did not become calcified, w do not know. 

 If the latter was the case, then no fruiting specimens have yet been observed, 

 for these would show the scars of the sporangia. In the former case we 

 should have a simplification of the type of Dasycladeae, and this would 

 present no difficulty from the algological point of view. The Cretaceous 

 genus Munieria, Hantken, which forms beds of stone near Bakony in 

 Hungary and has been described by Deecke 2 , will probably be united to 

 Diplopora and Gyroporella ; it requires further study. 



Lastly, in Triploporella Fraasii, Steinmann, from the Turonian Chalk of 

 the Lebanon, we have a form, which seems to be intermediate between the 

 two groups above mentioned. It has been described by Steinmann 3 , and 

 externally it exactly resembles Diplopora, but each simple shortly cylin- 

 drical branch in a whorl has at its apex three small almost globular branches 

 of the second order. As to the meaning of these branches, since there is no 

 indication that there was once a sporangium between them, we can only say 

 what was said of those of Gyroporella. 



A few fossil genera are placed by Munier Chalmas in the group of 

 Acetabularieae, the nearest allies of Dasycladeae. Of these I know only 

 Acicularia, d'Archiac and Briardina, Mun. Chalm., the latter through the 

 kindness of Munier, who himself demonstrated it to me. We find a variety 

 of forms figured in Carpenter 4 under the name Acicularia ; of these, figures 

 27 and 31 may represent Munier's Acicularia, figures 28-30 another genus, 

 perhaps Orioporella. I question much whether figure 32 belongs to this group 



Giimbel (1). * Deecke (I). s Steinmann (1). Carpenter (1), t. n, ff. 27-32. 



