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collection a gieat number of specimens of F. patelliformis showing 
this process of regeneration. The greater part of these specimens 
were collected by Dr. M o r t e n s e n in different localities in the 
Siamese waters. They all possess the Diaseris WkQ lobes with a 
curved shape of the costae and septa. One specimen from this 
locality which has a nearly complete circular form, is represented 
in my previous paper on these corals (Boschma 1923, figs. 13, 
I3a). At the lower surface of this specimen the fissures between 
the different lobes are still clearly visible. The upper surface is at 
first sight hardly to be identified as a regenerated specimen, the 
course of the septa showing only very few irregularities. 
In most of the specimens regenerated in this way the fissures 
between the different lobes are still clearly visible. In the course 
of further growth the different sectors may fuse together and then 
only a suture is left. The corallum then shows a Cycloseris-form 
that has developed from a Diaseris-hrm. When the different lobes 
are strongly fused the corallum usually has become much thicker 
and often assumes a somewhat arched form. The notches in the 
marginal part may in these specimens almost completely vanish. 
The corallum represented in fig. 13 is also in some respects 
an intermediate stage between Cycloseris and Diaseris. The original 
part of it was less than a half of a broken corallum, as a ridge at 
the lower surface indicates. Some parts of the corallum have grown 
out as lobes which are separated in the marginal part by sutures. 
The septa next to these sutures have assumed a more or less 
curved shape as is also the rule in true D/asms-specimens. The 
central part of the corallum, however, shows no traces of sutures, 
whilst in Diaseris-^ovms these sutures usually are visible from the 
margin to the centre. 
In one of the specimens which have regenerated from a small 
fragment the old mouth has undergone fission by the fusion of two 
opposite septa. 
True D/asms-forms of F. patelliformis are found in great quantity 
among my material. Most of them have fallen asunder into separate 
wedge-shaped fragments. A few of these pieces are strongly lobate 
at the margin (fig 14). 
13* 
