54 



CORALS 



the coral an appearance similar to the convoluted surface 

 of the human brain. 



Between the Brain corals and the Favia type of coral, 

 however, there are many intermediate forms which in a 

 series show an increasing number of elongated sinuous 

 calices among the round or angular ones. 



DiCHOCOENiA. — An example of such an intermediate 

 stage is shown in the figure of a specimen of the genus 

 Dichocoenia (Fig. 19). In this genus some of the calices 

 seem to be circular in outhne, and, as they are in some 



Fig. 19. — Dichocoenia pulchcrrima. A small specimen. Xat. size. 



species separated by a scanty vesicular coenosteum, have 

 an appearance somewhat like that of Favia, though amongst 

 them there are many elongated straight or sinuous cahces 

 which show no trace of constriction. But these elongated 

 calices are relatively short as compared with the long 

 labyrinthine calices of a true Brain coral. 



The septa of Dichocoenia are well developed, slightly 

 exsert, and, as in Favia, are continued over the lip of the 

 calyx wall as costae which meet the costae of neighbouring 

 calices on the peritheca. 



The most familiar of the Brain corals are those included 



