190 
PACIFIC SCIENCE, Vol. IV, July, 1950 
created by the full force of the prevailing 
westerly winds that blow over the Tasman 
Sea. 
Observations were carried out mainly on 
Lion Rock and at the ’'Gap” behind Camel 
Rock. The former is an isolated rock 330 feet 
high and has a broad wave platform at about 
storm height. The sides of this platform slope 
steeply down to low water mark at most 
points. The second area is formed by a large 
off-shore rock (Camel Rock) with a narrow 
channel between it and the mainland; through 
this the sea surges with great force. There 
is also a tunnel through the northern end 
of Camel Rock in an east-west direction. 
(Fig. 1.) 
Geologically the rocks belong to the Ma- 
nukau Breccia series and consist of andesitic 
fragmental beds with numerous intrusive 
dykes and minor interbedded flows. There is 
no variation in the area studied. 
CLIMATE 
The climate is mild and equable with pre- 
vailing westerly winds, but the open coast is 
often exposed to strong gales which send 
the waves to great heights against the vertical 
cliffs. The sea is seldom calm and there is 
normally a strong surf, and even on the quiet- 
est day a considerable swell is present. 
The mean annual precipitation is about 
44.73 inches and the mean annual amount 
of sunshine, 1,914 hours. The average an- 
nual air temperature range is 26° C. with a 
daily shade range of about 7.0° C. The max- 
imum shade temperature is 32.8° C. and the 
minimum — 0.5° C. 
LITTORAL COMMUNITIES 
These are described more or less from high 
water mark downwards. 
1. Lichina pygmaea-Melaraphe 
association 
Range: upper limit of spray to 
M.H.W.S. 4 
Lichina pygmaea (d) 4 
Melaraphe oliveri (d) 
Melaraphe cincta (d) 
Entophysalis deusta (1) 
various limpets 
In positions of maximum wave exposure 
this association may reach great heights. It 
is usually absent from crevices and other 
strongly shaded places. Of the two gastro- 
pods M. oliveri has the wider range since it 
may descend to M.H.W.N. whereas M. cincta 
occurs in the lower part of this association 
and in the narrow band formed by the next 
community. 
2. Bostrychia arbuscula consociation 
Range: wash of M.H.W.S. to M.H.W.N. 
Bostrychia arbuscula (d) 
Rhizoclonium riparium (If) 
Lophosiphonia macra (If) 
Caloglossa leprieurii (If) 
Melaraphe oliveri (f) 
Melaraphe cincta (f) 
Entophysalis deusta (seasonal) 
Enteromorpha ramulosa (seasonal) 
The dominant species occurs on shady ex- 
posed rock faces in a permanently juvenile 
and sterile prostrate form; the adult, dark 
red, fertile form is to be found in moist and 
dark crevices. 
*The following abbreviations are used through- 
out this discussion: 
E.H.W.S. = Extreme high water spring tides. 
M.H.W.S. — Mean high water spring tides. 
M.H.W.N. = Mean high water neap tides. 
E. (L).H.W.N. - Extreme (lowest) high water 
mark neap tides. 
M.S.L. = Mean sea level. 
E. (H).L.W.N. = Extreme (highest) low water 
mark neap tides. 
M.L.W.N. = Mean low water neap tides. 
M.L.W.S. = Mean low water spring tides. 
E.L.W.S. = Extreme low water spring tides, 
d = dominant 
a == abundant 
f = frequent 
0 = occasional 
r = rare 
1 = local 
