408 POLYPI. 
animal bark which envelopes it is mixed with calcareous granules, 
as in the Gorgoniz. In the 
CorALiium, Lam. 
The axis is without articulations, and is merely striated on its 
surface. P 
It is to this subgenus that belongs the 
Isis nobilis, L.3; Esp., 1, VII, or Coral of commerce, so cele- 
brated for the beautiful red colour of its stony axis, and for the 
high polish of which it is susceptible. It constitutes the object 
of a lucrative fishery in several parts of the Mediterranean. Its 
bark is reddish and cretaceous. The Polypi, as in many other 
genera, have eight denticulated arms. 
Menirza, Lam. 
Where the stony substance of the axis is interrupted by knots filled 
with a matter resembling cork(1). In 
Is1s, Lam. 
Or Isis properly so called, it is interrupted by strangulations of 
which the substance resembles horn. The thick and soft bark falls 
more easily than that of the preceding ones(2). 
M. Lamouroux also distinguishes from Isis proper, 
MopseEa, 
Where the bark is thinner and more durable(3). 
Manprepora, Lin. 
The stony portion of Madrepores is either ramous, or forms 
(1) Jsis ocracea, Esper., I, iv;—Is. coccinea, Id., IT, A, 5. 
(2) Isis hippuris, L.; Sol.and Ell., Zooph., Ill; Esper, I, 1;—Js. elongata, Esper, 
I, vi. 
(3) Isis dichotoma, Seb., UI, cvi, 4;—Js. enerinula, Lam., or Is. verticillata, La- 
mour., Pol. Flex., XVIII, f. 2, and App. to Sol. and Ell., LXX, f. 4. 
