TABULATE CORALS. 



drical or subcylindrical, and as they radiate from the base, 

 become more or less widely separated towards their termina- 

 tions. Hence the surface of a mass of C. calicina (fig. 28) 



Fig. 28. I a, A colony of Columnaria calicina, Nich., from the Hudson River Group of 

 Canada, of the natural size ; I l>, A single calice of the same enlarged ; 2, A calice of 

 Columnaria (?) ffalli, Nich., (C. alveolata, auctt. non Goldf.), enlarged. 



often presents an appearance similar to the convolutions of 

 the human cerebrum or to a colony of Fascicularia. 3. It is 

 only where the corallites are in actual contact that their walls 

 are united, and in the remaining portions of their course each 

 is enclosed in a distinct and separate wall, marked with con- 

 spicuous vertical ridges and fine encircling striae. 4. The 

 increase of the corallum is effected by calicular gemmation, 

 and apparently also to some extent by lateral budding, the 

 former mode of growth not seeming to occur in C. alveolata. 

 When we come to consider the internal structure of C. 

 calicina, we find that the differences which separate it from 

 C. alveolata, Goldf., depend principally upon the peculiar 

 mode of growth of the former, the anatomical characters of 

 the two species being very much the same. Transverse 

 sections (PI. X., fig. 2 d) show that though the tubes in the 

 contiguous portions of their course are practically amalgamated 

 by their walls, the real duplicity of their walls is never lost, the 

 actual line of division between neighbouring corallites being 

 still conspicuously recognisable under the microscope. In this 

 respect, therefore, C. calicina entirely agrees with C. alveolata. 

 These sections, further, show a highly " Rugose " condition of 



