466 Prof. P. M. Duncan on the Pali of Corals. 
7 to 9 fathoms of water, and offers an instance of this nature. 
Here I expected to find the corals in luxuriance; but the 
appearance of its surface from the ship’s side and the character 
of the soundings showed that the greater portion of its area 
consisted of dead coral-rock dotted with bosses of massive corals 
here and there. Such was the condition of another shoal in 
Bougainville Straits, which was covered by from 5 to 6 
fathoms of water. Here the eye could discern an occasional 
dark-coloured boss of coral in a field of a pale grey hue, 
which was shown by the nature of the crushed material 
adhering to a heavy lead to be dead coral-rock. 
A word with reference to the general character of the reefs 
in the Solomon group may not be out of place in concluding 
this paper. From the works of Krusenstern, Surville, Bou- 
gainville, and Labillardiére, Mr. Darwin presumed that these 
islands were fringed (‘Coral Reefs,’ p. 167, edit. 1842). 
There are, however, numerous reefs in this archipelago which 
belong to the class of barrier-reefs. A barrier-reef of exten- 
sive nature is situated on the west side of Bougainville 
Straits, where it follows the edge of a wide submarine plat- 
form, which may be viewed as the submerged continuation 
of Bougainville Island. A smaller barrier-reef, previously 
referred to in the instance of Choiseul Bay, skirts the western 
extremity of the island of Choiseul on the opposite side of 
these straits. Similar lines of dangerous reefs le off portions 
of the coasts of Guadalcanar, Malayta, and other islands. I 
hope on some future occasion to enter more fully into this 
subject, this reference to which must for the present suffice, 
LIII.— On the Relation of the Pali of Corals to the Tentacles. 
By Prof. P. Martin Duncan, F.R.S. &e. 
Pror. Linpstr6mM has brought under my notice that my 
late friend M. de Pourtalés differed from me in reference to 
the relation of pali to the tentacles of Corals. In noticing a 
very interesting form from the Caribbean Sea which has a 
Miocene ancestry, M. de Pourtalés considered the question of 
pali. He wrote, “ Prof. Duncan’s supposition that the office 
of the pali is to support an extra circle of tentacles is not 
borne out in this species, nor in any other paliferous coral of 
which I have had the opportunity of examining the polyp.” 
We had a conversation on this point, and M. de Pourtalés 
told me that he had not had opportunities of seeing man 
living forms with pali with the soft parts extended, but that 
