54 STANLEY SMITH. 



to a loose retiform pseudo-columella. The minor septa 

 attain a length from about one-half to two-thirds that of 

 the major septa. 



The number of septa in each cycle is about twenty-two; 1 

 they may therefore be described as not crowded. The 

 fossulae are not obvious, even in immature stages. 



The tabulee are numerous. I have counted about thirty 

 plates in the space of one centimetre. They are flat or 

 slightly arched, but are irregular and not consistently con- 

 tinuous across the intrathecal area. (Plate II, fig. 3.) 



The dissepiments are medium-sized plates, and form a 

 wide peripheral zone external to the septal cycle. Where 

 fully developed, this constitutes about one-third of the 

 radius of the corallite. In very many cases, the peripheral 

 parts of the corallites are much crushed and broken. 



The epitheca is strongly developed. 



Observations concerning the development of corallite. 



The young corallites make their appearance between the 

 older ones, and are evidently attached to the epitheca of 

 their parent; they are the product of lateral germination. 2 



The septa in the earliest stage observed are united with 

 the epitheca; they are short and do not reach the centre 

 of the corallite. Later, but nevertheless, still at an early 

 stage, they become detached from the epitheca, and the 

 intervening space becomes occupied by relatively large 

 dissepiments; at the same time they advance into the 

 pseudo-columella. (Plate II, figs. 4 and 5). 



During the immature stages, much deposition of calcium 

 carbonate takes place at the theca, and renders that part 

 of the structure very dense. The feature becomes much 

 less pronounced when maturity is attained. (Compare figs* 

 1 and 2 on Plate II.) 



1 See note on an isolated corallite following description of Aphrophyllum. 



2 See Q.J.G.S,, Vol. xlii, (1916), pp. 233-235. 



