CH. VI MARINE FAUNA OF TALISSE SHORES 123 



the general reader may follow me in my description of the 

 reefs. 



Of the true or Zoantharian corals, the most important 

 and largely represented family is that of the Madreporinas. 

 The madrepores may be readily distinguished by the fact 

 that they possess distinct cups for the polypes, and that 

 these cups, together with the rest of the corallum, are 

 thoroughly perforated in aU directions by numerous pores 

 and anastomosing canals. 



Fig. 15. — Schematic drawing of a single polype of a colonial perforate coral 

 and of the surrounding tissues after the skeleton has been removed by 

 acid, showing the system of tubes by means of which the digestive 

 cavities of the polypes communicate with one another. 



In fig. 15 is drawn a small portion of the soft fleshy 

 parts of a Madrepore after the removal of the coral skeleton 

 by acid. While the general structure is the same as that 

 of Galacea, a large number of fleshy tubes lead from the body 

 space of one polype to that of its neighbours, so that a com- 

 plete circulation is maintained throughout the whole colony. 

 These tubes ramify according to a fairly definite system, 

 passing through a corresponding system of stony channels 

 in the coral skeleton. Many of them have extremely grace- 



