90 SIDNEY F. HARMER. 
in old colonies at the same time of year as primary broods from 
young colonies is in favour of that view. 
In fig. 14 places will be noticed, as at B, where the neigh- 
bouring alveoli do not meet accurately. These places are the 
** cancelli”” which are so commonly met with in accounts of 
the genus Lichenopera. The cancelli do not at first develop 
to any great extent; but this condition is altered in the old 
colonies (figs. 8, 9). 
Fig. 9 shows three zocecia of an old colony. One of these 
zocecia has been occluded by a calcareous cap at a considerable 
height above the level of the ovicell. This is quite similar to 
the structures which are well known to occur in profusion 
over the more centrally placed zocecia of certain species of 
Diastopora. 
The alveoli which are shown in fig. 9 are separated from 
one another by shallow grooves. At these regions, and at the 
junction of a zocecium with the roof of the ovicell, vertical 
septa are rising up. Fig. 8 shows the appearance of a colony 
after this secondary thickening has been proceeding for a longer 
period. The system of vertical septa, which in the earlier 
stage started only at the intersection of the alveoli with one 
another or with the zoccia, has now extended so as to cover 
the entire surface of the ovicell. The porous roof of the latter 
can be seen at the bottom of the open cancelli, which have 
for the most part no calcareous roof. The base of the right- 
hand zoccium is surrounded by very large cancelli, the walls 
of which (as in fig. 9) are continuous with the longitudinal 
ridges of the outside of the zocecium. These cancelli are 
obviously encroaching on the base of the zocecium, which can 
be seen at the bottom of the spaces. Those marked ‘cancelli”’ 
are beginning to acquire a calcareous roof. The process of 
roofing in is much further advanced at the base of the left-hand 
zocecium, where one of the cancelli is completely closed. In 
this way the bases of the zocecia of old colonies commonly 
become surrounded by a set of blister-like swellings, which 
have been formed above the original roof of the ovicell. These 
are presumably the structures which Smitt regards as forming 
