276 Mr. H. M. Bernard on the 
Where the epitheca follows the growing edge closely, the 
latter tends to grow upwards free of the substratum, but where 
the epitheca lags behind the growing edge, the latter tends 
either to droop, which is the more usual, or (A. myrtophthalma) 
to send down long pendent and twisted calicular tubes, which 
are gradually enveloped and closed by the advancing epi- 
theca. It is obvious that this explanate growth may merely 
creep over the substratum as a simple incrusting corallum. 
I have distinguished in all five explanate species, three of 
which are new. 
Second Method of Growth: Pulvinate.—The growth is in 
this case chiefly in thickness. The calicles grow rapidly in 
length, tabule being developed at intervals, as is the case in 
the lengthening calicles of glomerate Turbinarians. New 
calicles appear for a time at the expanding edges of the 
corallum, and others between the lengthening calicles as they 
diverge (fig. 2). In time the lower portions of the stock die, 
and no new calicles are added round the edge of the original 
epitheca (¢). ‘The Jiving top, on the other hand, goes on 
expanding by the continued divergence of the calicles and the 
addition of new ones between the old. This uppermost living 
layer tends to hang down over the old dead portions, in which 
case a new (secondary) epitheca (e"’) appears, restraining the 
downward growth of the edges. As layer succeeds layer, 
enormous top-heavy bolster- or cushion-shaped masses are 
produced. The top-heaviness is obviously due to the fact 
that the early death of the lower portions limits the size of 
the base. 
Sooner or later such masses break off and roll over. The 
living layer will then be confined to the uppermost portion of 
the overturned stock, on which it soon forms another great 
top-heavy mass (see fig. 3, in which a is the original upper 
surface of an overturned stock). 
Among the specimens in the collection are several showing 
this method of growth. There is a complete series from 
Tongatabu, which I have named A. Listerd, after Mr. J. J. 
Lister, who generously presented them to the Museum. 
Fig. 3 represents the largest specimen, forming a great mush- 
room-like mass 7 inches in diameter, 
Many of the other specimens which I attribute to this 
method of growth are unfortunately only fragments. All 
these fragments, however, show enormously long calicles 
with tabule, and, further, the living ends of the calicles bend 
outwards and form at the edge an overhanging margin such 
as that shown in the diagram fig. 2. These growths are 
thus obviously not explanate, nor are they globular. As far 
