April, 1917 . The Queensland Naturalist. 
55 
On the Caloundra headlands, the inter-tidal area can 
be divided into four or, perhaps, five definite horizons, though, 
of course, each overlaps that immediately above and below it. 
Commencing with the highest in position, they are 
(1) The Tectarius zone, in which a gastropod Tectarius 
pyramidalis is the only evident marine inhabitant. 
(2) The upper Melaraphe zone, whose dominant animal 
is another littorinid, M. mauritiana {M. unifasciata) which 
in its lower limits includes the next zone. 
(3) The lower Melaraphe zone or Chthamalus zone, the 
latter name being preferable as Chth. antennatus (a sessile 
barnacle) is the dominant organism at least on the exposed 
part of the area. 
(4) The Tetraclita rosea—Liolophura zone, characterised 
by the presence of another cirripede T. rosea, and, in its 
middle and lower regions especially, of a chiton Lio, queens- 
landica. Tetraclita is common in the upper parts of the 
next zone, but there it is much smaller. 
(5) The Sargassnm-Oniihochiion zone, in which the 
dominant organisms are the sea-weeds Sargassum spp., 
though other algse are also common. The chiton On. 
quercinus is also abundant there, and is practically restricted 
to this horizon. 
As secondary zones, I might mention {a) the ocean 
rock pool ib) the Siphonaria area ; and (c) the Melaraphe 
infans area. 
The above-named zones can be correlated with those 
of Mr. Hedley thus : — His upper horizon includes my Nos. 
1, 2 and 3 ; his median one coincides apj)arently with the 
main development of No. 4 ; while his lower zone corresponds 
to our No. 5. There is thus the same succession of horizons, 
though there is — as we might expect — some difference in 
regard to the dominant organisms. The very close resemb- 
lance of the fauna of Sydney and Caloundra ocean reefs is 
noteworthy. In both cases, the rocks are of Trias-Jura 
age, though the local series was laid down later, and should, 
according to Mr. A. B, Walkon,. be regarded as Jurassic. 
Both reefs are sandstone, a type of rock which weathers in 
such a way as to afford support or protection for a host of 
organisms. There is, however, a considerable difference in 
latitude — about degrees, and representing approximately 
450 miles — and in sea temperatures, especially the minima 
of the two localities. 
A. The Sargassum — Oniihochiton horizon This zone 
is uncovered only at low spring tides. Its dominant plants 
are species of Sargassum, especially S. leptopodum, though 
others are not uncommon, S. hiserrula. S. auralice, etc. 
