AMORPHOZOA FROM THE SILURIAN AND DEVONIAN. 255 



space of two lines. The layers are undulating, and conform in their 

 flexures to one another, and they show no signs of being composed of 

 secondary laminae. They commonly exhibit, however, on their edges 

 what appear to be the mouths of tubes traversing them horizontally. 

 The upper surface of all the successive layers, except the outermost, is 

 studded with pointed or elongated processes, which, when broken across, 

 show a central cavity, and which extend to the under surface of the layer 

 next above. The height of these processes is about one-third of a line 

 and three or four of them occupy the space of one line. The successive 

 layers rest upon the points of these processes apparently without being 

 united with them. The outermost layer of all is smooth and undulating, 

 and exhibits a few irregularly disposed, circular or oval apertures, which 

 are placed at varying intervals apart, and have a diameter of about one 

 line. 



Dictyostroma undulata in appearance resembles a greatly magnified 

 Stromatopora; but the differences to which attention has been, drawn in 

 the above description seem to be sufficient for its characterization as the 

 type of a new genus. 



Position and locality : Niagara group, Louisville, Kentucky. From the cabinet of 

 Prof. Edward Orton. Collected by Rev. H. Hertzer. 



