April, 1917 . The Queensland Naturalist. 59 
then the shell becomes higher, the sides bulge more, and the 
entire shell comes to resemble that of Cellana. When the 
rock surface is rather more irregular, Cellana may be present. 
Enteromorpha is common here. Hemitoma and Oulaciis 
muscosa are to be seen' in the lower portions, i.e., on a level 
with the Laurencia area. The Siphonaria region reaches 
its best development on a level with the Tetracliia zone. 
The ocean rock pool.— This is a zone of constant immersion, 
and links up with the Sargassum horizon, with which its pools 
may be connected by means of gutters or cracks in the rock. 
It is the most interesting of all the inter-tidal regions, as it 
has the richest and most diversified fauna. Its plant life 
is varied, being similar to that of the Sargassnm zone in the 
case of deeper pools, while in the shallower ones, Corallina 
officinalis, Jania rnhens and Padina pavonia are common. 
In the former, one may see Sargassunt spp. {leptopodttm, 
hiserrula, claviferum, etc.), Cystiphyllum muricatnm, Hormosira 
articulata, Padina pavonia, Gymnosorus variegatas, Gelidium 
corneum, Chondrococcus harveyi, Dictyota dichotoma, Dilophus, 
Galaxaura elongata, Halimeda tuna, Sphacelaria, Plocamhim 
hamatnm, Laurencia concinna, etc., while on rocks is an 
encrusting form, Lithothamnion, and under ledges is another 
Nullipore, which I believe to be a Lithophyllnm. This latter 
forms thick porous masses, from which there project upwards 
short calcareous plates. 
The Coelenterata are well represented here. The hydroids 
Sertularia, Plumularia and Aglaophenio grow on the under 
side of stones. Three or four species of Alcyonaria occur, 
two of them being quite common. One is a beautiful greenish- 
blue organism, Xenia sp., while an Alcyonium forms rather 
massive chocolate colonies, resembling a Madrepore coral in 
form. A Cornnlaria and a Sarcophyton are occasionally 
found, so also is a carmine Echinogorgia. The last-named 
species, as well as a yellow species of the same genus, are 
common!}^ washed up on the beach. There are also a few 
hard corals, including two or three species of Goniasircea, 
a Pocillopora S])., Madrepora sp., Cyliria sp., and a form 
somewhat resembling Dendrophyllia. 
There are two species of Epizoanthtis, one of which is very 
common. Other anemones also are to be seen. 
The sponges are well represented, so also are the Polyclads 
(Leptoplana sp.) Nemerteans and free-living Nematodes 
occur. Polychaetes are common, including besides Polynoids, 
Amphinomids and Eunicids, Heteronereis and many tube- 
dwellers, e.g , Spirorhis, Spirographis, Galeolaria, Sahellaria, 
Pectiyxaria and Terehella. Beautifully coloured Serpulids 
are to be seen, reminding one of those found in the coral on 
the Barrier Reef. 
