4 Mr. ellis on the Gorgonia. 
is indeed a regular cannulated appearance on the furface ; 
but this feems to be only an external moulding, and not 
formed by a feries of longitudinal tubes with interllices, 
as in plants; nor is it difficult to explain from whence 
fuch a moulding may arife. 1 have oblerved, that the 
inner furface of the flefhy part contiguous to the bony 
or horny part, is furnifhed with longitudinal parallel 
tubes, which through certain pores fupply the ojfeous 
matter; this being foft at firft, and only afterwards be- 
coming hard, fo as neceffiirily to take the form of the 
concave furface by which it is clofely preffed, and there- 
fore affumes a ftriated appearance. This is plainly 
feen in fig. 2. a. where the ends of the tubes and the 
ftriated appearance on the gorgonia flafrellum are ex~ 
prefled; and at fig. 2. B. two of them are magnified. 
In the IJis hippuris , or black and white jointed coral, 
which is very nearly a-kin to this genus, thefe tubes are ftill 
more clearly to be feen, as they are larger and the chan- 
nels much deeper, fee fig. 3. where a is a part of the co- 
ral of its natural fize; b is an extremity of one of the 
branches magnified, with the bony part laid bare; c a 
part of the fame, with the bony part taken out, to ffiew 
% 
the tubes with their internal orifices, through which the 
ojfeous juice is fuppofed to exude, and form the layers of 
the bony and homy part. This formation of the hard 
part or bone of the ftem feems to be a principal ufe of 
the longitudinal tubes; but they have another alfo, of 
great confequence in the growth of the gorgonia : for it 
is by means of thefe, that the animal fpreads itfelf down- 
wards over the fubftances which ferve for its bails, thence 
deriving 
