88 



SIDERASTREA RADIANS. 



wall of two contiguous polyps is common along the lines of adherence, and 

 the outline, instead of being circular, becomes more or less polygonal as a 

 result of the mutual pressure. 



The protoseptal stage was completed in nearly all cases within the first 



xb -^' 



Fig. 9 (-#). Series of diagrammatic figures illustrating the manner of development of the septa from one to three cycles 

 {cf. plates 1-5). The epithcca is represented as a white circle distinct from the septa. 



fortnight, and some of the smaller polyps never reached beyond ; indeed, in 

 a few examples, the exocoelic cycle was never completed. Much variation 

 was observable as to the rate at which the corallum was laid dowTi, growth 

 in larger polyps being always in advance of that in smaller individuals. 



