5 
1899-1900.]_ Natural History Notes on Tenby. 95 
cavern. ‘This is the smallest, and perhaps the least pro- 
ductive, of the three caverns which penetrate the rock, yet it 
is well worthy of attention. Here, as well as in other parts 
lof the rock, occur in abundance the dog whelk (Purpura 
Vapillus), with its beautiful little ege-cases, which stud the 
jwalls in all directions; anemones, chiefly the beadlet (Actinia 
mesembryanthemun) in several varieties, are plentiful; the 
acorn - shell barnacles, both Balanus Balanoides and B. 
porcatus, abound; while the walls of the cave, from the 
groma to a height of twelve or fifteen feet, are covered, 
though perhaps not so abundantly as in the second cavern, 
with hydroid zoophytes. 
The second cavern, the entrance to which is but a few 
yards seaward from the first, like it penetrates the rock and 
emerges at the other side. Like it, too, it is always accessible 
at low water of ordinary tides. Larger than the first, it is 
4 ivided in the centre by a vast pillar of rock, and the eastern 
¢ the two compartments thus formed is far the richer in 
animal life. Here occurs in abundance that beautiful little 
anemone, the snowy-disk (Sagartia nivea). In one small 
tock-pool three or four feet from the ground, and when the 
fide has receded presenting a surface of less than a square 
yard and not many inches in depth, I counted on one occasion 
about a hundred of these animals. As in the first case, the 
beadlet anemone is abundant, while the walls are covered 
with barnacles, and with zoophytes belonging chiefly to the 
genus Obelia, and in less abundance several other genera— 
‘Hydrallmania, Sertularia, Plumularia, Diphasia, &e. | Sponges, 
except the crumb-of-bread sponge (Halichondria panicea),though 
abundant on other parts of the rock, are not common here. 
The third cavern is more pretentious than either of the 
other two, but is accessible only at low water of spring tides, 
and easily so only at the equinoctial tides of March and 
September. This, like the others, penetrates the entire width 
f the rock, but it is not so easy to traverse. Towards the 
otre the passage is much constricted, and it is necessary, in 
der to pass through, to scramble up the rock, squeeze 
ough a narrow opening, and then, having jumped down 
me eight or ten feet, to wade a deepish pool which remains 
| even after the tide has receded. It is easier, instead of doing 
>. ) 
