THE ANTHOZOA 



from which it will be seen that the theca appears to cut the 

 mesenteries in two. It will also be noticed that, in an aporose 

 coral such as is shown in Fig. XXX. 2 and 4, the only com- 

 munication between the cavities in the edge-zone and the remainder 

 of the intermesenterial spaces is by way of the lip of the calicle, 



c?^^^*g. 



s f n 



fZ. 



6. 



FIG. XXX. 



1. Astroides calicularls. Schematic longitudinal section through a zooid and a bud, show- 

 ing the relations of the soft tissues to the coralluin. In this, and in figures 2 and 4, the 

 thick black line represents the soft tissues, the coralluin is gray. The sections are much 

 simplified, the mesenteries, etc., being omitted. S, stomodaeum ; T, tentacles ; C, coenosarc ; 

 Col, columella. 



2. A similar section through a single zooid and bud of Stylophora digitata. On the left 

 of the figure the coenosarc is seen to be supported on echinulations of the coenenchyme. 



3. A diagram illustrating the process of asexual reproduction by unequal division. 



4. Schematic longitudinal section through three coralities of Lophohelia prdifera. In the 

 upper part of the figure the larger zooid is seen to be in connection with the smaller zooid 

 formed from it by division both internally and externally by way of the edge-zone. The lowest 

 zooid has lost all organic connection with the other members. P, edge-zone ; other letters as in 1. 



5. A section through a dividing calicle of Mussa, showing the union of two septa in 

 the plane of division and the origin of new septa at right angles to them. 



6. Side view of the upper part of the specimen shown in 5. (4 original, the rest after 

 G. von Koch.) 



but in the perforate coral the theca is permeated by numerous 

 anastomosing canals lined by endoderm, which place the cavities 

 of the edge-zone in communication with the central coelenteron. 



According as these canals are absent or present, the Sclerac- 

 tiniae are classified as Aporosa or Perforata, and the anatomical 

 character in question is sufficiently definite to afford a basis of 

 classification. There are, however, some corals which cannot be 

 placed in either of these groups. 



