G. M. Ehlers — New Species of Tetracoralla. 465 



central part of the calyx is a fractured portion of a third 

 tabula. The marginal remains of this tabula and pos- 

 sibly another are partly preserved between some of the 

 lamelliform septa (see fig. 3). Other tabulae may be 

 present in the space between the two nearly complete 

 tabulae. 



The tabulae are variously modified in the interseptal 



Fig. 3. 



Fig. 3. — Calycinal view of the type specimen of Heterolasma foerstei, 

 showing the different kinds of septa, tabulae and the openings" of the 

 radiciform processes. Natural size. 



spaces. They extend upwards to meet the sides of the 

 septa ; as a result, the upper surfaces of the tabulae in 

 each interseptal space become concave (see t 1 , fig. 3). 

 Frequently, the tabulae are much depressed towards the 

 angles made by the junctures of the lamelliform septa 

 and the wall of the corallum, thus forming small, irreg- 



