OLIvER.— Marine Littoral Plant and Animal Communities. 531 
Pelecypod Subformation. 
In the northern portion of New Zealand, north of S. lat. 38^, Ostrea 
cucullata forms a conspicuous association in the mid-tide belt. It chiefly 
affects sheltered coasts, and sometimes covers the rock-surface to a depth 
of 5cm. On the other hand, the association of Mytilus in the tidal belt 
is best developed in the southern portion of New Zealand, especially in the 
low-tide belt. Modiolus, an ally of Mytilus, occurs near high-tide mark 
throughout New Zealand. 
imilar associations are represented in other temperate regions. In New 
In the British Isles Mytilus edulis is a dominant form, whilst represent- 
ing the Mytilus association in New South Wales is that of Brachyodontes 
hirsutus (Hedley, p. 74), and in Tasmania Mytilus planulatus. 
Mytilus Association. 
phora obtecta (clean but eroded), P. biramosa with Me ia on the valves, 
Cellana radians, Stichaster suteri, Haustrum haustrum, Turbo smaragdus, 
alga. 
Immediately above the belt of Mytilus canaliculatus, M. planulatus 
becomes the dominant species. There are here very few algae, and the 
1 1 1 m hose associated 
with M. canaliculatus. The most common species are Elminius plicatus, 
E. modestus, Monodonta aethiops, Cellana radians, Sypharochiton pellis- 
serpentis, Vermilia carinifera (in patches), Brachyodontes таотатиз, and, 
on the valves of M. planulatus, Notoacmea pa . Here and 
there clusters of Elminius plicatus also occur on the valves of Mytilus 
planulatus. (Plate 45, fig. 2.) 
Takapuna.—Ostrea cucullata here occup 
in vertical width, and centred about half-tide ne 
be thickly scattered about, they may be in dense clusters, or the enure 
surface for many square metres may be covered t 
: t animals 
hen the Ostrea is dense not шапу PIU he locality here described : 
