594 
G. BERBERT FOWLER. 
order become disconnected very high up, and do not run dee p 
down into the colony, the cavities in which they lie disappearing 
among the other perforations of the theca. 
The number of pairs of mesenteries right and left of the 
“ directives ” is not necessarily equal. Complete systems, both 
of mesenteries and septa (i, 3, 2, 3, 1, in notation), are 
generally found only at the ends of the long axis of the calyx, 
i.e. in the neighbourhood of the directives. This has been 
noticed in many other corals. 
That the almost exact correspondence of costae with septa, 
and of the external lamellae (AT in the figures) with the 
mesenteries, adds to the probability of the correctness of 
v. Koch’s view, is undeniable. But it is to be noted, that no 
muscles are to be recognised on the mesoderm plates of these 
lamellae, as would probably be the case had they once been part 
of the mesenteries ; nor in the highest sections of the decalci- 
fied polyp are any cases of decaying tissue visible, where the 
growiRg theca is supposed to have cut them. 
iii. Histology. — This is of such a simple chai’acter as to 
hardly require comment. The ectoderm is composed of simple 
columnar cells, the endoderm of similar but more cubical cells. 
Calycoblasts are present, but in small numbers in comparison 
with Flabellum. Nematocysts are of two forms and sizes, of 
which, as in Flabellum, the smaller is the only one occurring 
on the tentacles. Of the mesenterial filament, as unusual in 
outline, a sketch is given in fig. 16. 
In conclusion, I have to acknowledge my obligations to 
Professor Moseley for much kind assistance and most of my 
material; to Professor Milnes Marshall for valuable advice; 
to Mr. John Murray, of the “ Challenger ” office, for several 
specimens of Flabellum ; and lastly, to the anonymous donor 
of the Berkeley Fellowship, whose generosity has enabled me 
to pursue the investigation. 
