PLATE VIII. 



Fig. i. Section of the corallum of Plcurodictyum stylophornm, Eaton., taken 

 parallel with and just above the flat base, enlarged two and a half times, 

 showing the tabulae, pores, and rudimentary septa. The sections of the 

 "vermiform body" are left white, for clearness' sake. From the Hamilton 

 Group (Devonian) of the State of New York. 



Fig. i a. Part of a tangential section of the same, similarly enlarged. A few 

 mural pores are seen in section ; and the sections of the " vermiform 

 body" are, as before, left white, except in one place where some dark 

 ovoid bodies occur within its cavity. 



Fig. i b. Vertical section of a specimen of the same, similarly enlarged, show- 

 ing the inosculating tabula? and mural pores. The visceral chambers of 

 all the corallites, except one, are filled with the matrix, and the sections of 

 the " vermiform body " are, as before, left unshaded. 



Fig. 2. Portion of the corallum of Chonostcgites Clappi, E. and H. ( = Haimeo- 

 phyllum ordinatum, Bill.), of the natural size, viewed laterally. Corniferous 

 Limestone (Devonian), Walpole, Ontario. 



Fig. 2 a. Portion of the upper surface of a broken corallum of the same, of 

 the natural size, showing the convex tabulae, and the upper surfaces of the 

 lateral connecting-floors. 



Fig. 2 b. Part of a transverse section of the same, enlarged twice. The actual 

 corallites are cut across transversely, but the lateral connecting-floors are 

 only seen where their undulations happen to bring them into the plane of 

 the section. 



Fig. 2 c. Part of a vertical section of the same, enlarged twice, showing the 

 form and mode of increase of the corallites, their hollow and vesicular 

 lateral connecting -floors, and the inosculating and subvesicular tabulae, 

 the upper surfaces of which are serrated with spiniform projections. Both 

 this and the preceding drawing (fig. 2 b} are taken from sections of a 

 specimen in which the tubes are exceptionally wide apart. 



Fig. 3. Small specimen of Lyopora favosa, M'Coy, sp., from the Lower Silurian 

 of Craighead, Girvan, of the natural size. (After Nicholson and R. Et he- 

 ridge, jun.) 



Fig. 3 a. A few calices of the same enlarged. 



