DESCRIPTION OF CORALS. 14] 
distinct (fig. 5 e), presenting a confused reticulation somewhat similar to that of 
the interspaces ; while in the upper portion of the fragment a thin calcareous 
pellicle, of animal origin, sometimes extended over the edges of the lamelle and 
across the intervening spaces. How far these characters can be considered as 
indicative of a natural cessation of development and of structural changes de- 
pendent upon such a condition, or upon local injury, the study of additional 
specimens can alone determine ; but it may be stated that analogous appearances 
have been observed in other genera under circumstances which proved that the 
variations were not accidents, but regular consequents due to the age of the 
polype*. 
Respecting the progressive characters of interpolated stars, only a short notice 
will be necessary. In the earliest observed condition, an irregular star, com- 
posed of a few defective lamelle, appeared in the reticulated interspace ; but so 
far as they were produced, they were equal in dimensions on each facet. This 
character is deemed worthy of attention, affording one means for distinguishing 
interpolated stars from those produced by subdivision. In the latter cases the 
earliest stage exhibits unequal lamelle, those on the outer side of the subdivided 
star, or that side which is a prolongation of the previous boundary of the undi- 
vided star, having full dimensions, in consequence of the secreting organs of the 
bi-separated polype having in that part preserved the previously perfected powers ; 
while along the Jine marking the subdivision the lamelle are rudimentary, the 
necessary vessels for elaborating them not being matured. ‘The boundaries also 
of interpolated stars are similarly composed on all sides, the surrounding full- 
grown polypes having equally contributed to their formation ; whereas in divided 
stars they are dissimilar, and for the same reason, that the lamellz are unequal. 
In noticing the mode of forming marginal stars, it was stated that they were 
most advanced on the sides next the more nearly perfected structures ; but in 
cases of interpolation, considering the manner of development to be the same, 
the progressive increase must be uniform on every facet. Sometimes the young 
stars appeared singly, as in the case figured, but not unfrequently two or three 
were grouped in different ways, and in those instances there was an intermingling 
of structures. It is not necessary to detail the steps by which these polype- 
cavities arrived at maturity ; some of them were shown in specimen figure 5, 
and every intermediate stage was noticed. 
The internal characters of the Bracklesham coral agreed closely, as before- 
* Journal Geol. Soe. vol. i. p. 498. 
