LECTURE Xii. 
209 
soft bark, in which, as in the rest of the tribe, are 
disposed the numerous branchings of the animal 
part. The most elegant species of Isis is an 
Indian Coral, growing to the height of about a 
foot, and of a white colour with the horny joints 
black. This, however, is tho appearance of the 
Coral when dried, as it is usually seen in cabinets ; 
but when recent, it is entirely covered with a soft 
whitish bark with numerous pores, from each of 
which protrudes a polype-head with eight arnis. . 
Some of the Coral tribe have their animal part 
more nearly approaching (so far as we can trust 
to the observations hitherto made) to that of a 
Medusa than to that of a Polype. Of this kind 
are those very numerous Corals known by the 
title of Madrepores, and which constitute the Lin- 
n?ean genus Madrepora. Their forms are very 
various, some being of a globular shape, others 
flattened, and others branched in various directions. 
They are generally marked with numerous star- 
shaped cavities, divided into several rays, but- 
many are rather marked into various winding 
stripes composed of separate plates or laminse 5 and 
all, when recent, exhibit a gelatinous animal sub- 
stance situated either on the star-shaped cavities 
LECT. ir. p 
t 
