58 -1/. H EI N RICH 



''true" Stromatoporoidea. (2) That the division into a "mille- 

 poroid'' and a "hydractinoid" group must give way to another, 

 since the distinction on which it rests is not present. 



Next should be discussed the families which in my opinion have 

 been incorrectly referred to the Stromatoporoidea, i.e., Idio- 

 stromidae Nicholson, with the genera Amphipora Schulze, 

 Stachyodes Bargatzky, and I dio stroma Winchell, and Labechidae 

 Nicholson, with the genera Labechia Edwards and Haime, Rosenella 

 Nicholson, and Bcatricea Billings. 



In Amphipora, the old conception is to be replaced by that of 

 Felix (1905), which I found confirmed in hand specimens from Let- 

 mathe and elsewhere in which the fossil had not yet been weathered 

 out. According to this, around a non-tabulate axial canal, about 

 0.75 mm. wide, are grouped closed cells, which increase in size 

 outward. 



In Stachyodes, the original view of Bargatzky (1881) must be 

 restored, which stated that from a non- tabulate axial canal there 

 branch off non-tabulate lateral canals which in turn branch repeat- 

 edly. The wall structure of the canals is massive but seems to be 

 perforated in places. 



Idiostroma also has a non-tabulate axial canal, arising out of 

 the openings, which bear apically calcareous interfingering lamellae. 

 Otherwise the lamellae are only slightly perforated. They are 

 supported at intervals by little walls and pillars. These are 

 arranged more or less in the form of parabolas which extend from 

 the apex backward. They leave between them a labyrinth of 

 passages which also extend from the apex (the axial tube) back- 

 ward. The passages of one and the same interlamellar cavity are 

 well connected with one another, but seldom with those of the 

 neighboring spaces, since the lamellae seldom show a pore. 



In all three genera one misses the meshy structure as well as 

 the astrorhizae of the "true" Stromatoporoidea, aside from the 

 fact that these fossils never have a treelike appearance or anything 

 like it. 



Again, the skeleton of the Labechidae is not at all stroma- 

 toporoid, having no network of meshes open on all sides, but rather 

 a complex of circular, closed, flat vesicles, which, according to the 



