526 Transactions. 
and filled with brown granules. Beneath this are the large polygonal сейв. 
of the medulla, the outer ones of which have brown granules. Inside this 
to the central water-chamber are straight septate filaments. 
Chatham Island.—The sea-water in Waitangi Bay is very much dis- 
Hormosira Banksii. This alga grows very thickly, completely covering 
the rocks. Underneath there is little life, only Monodonta coracina and 
Sypharochiton pellisserpentis being seen; but on the rock where Hormosira 
is more open there are numerous gasteropods. Cerithidea subcarinata is 
Ulvoid-algae Subformation. 
Two associations are here included : one consists of Porphyra columbina, 
on rocks about half-tide mark ; the other of Ulva rigida, often in situations 
subject to the influence of fresh water. Both these species, though having 
broad, delicate thalli, are able to remain for a considerable period exposed 
to the atmosphere. Porphyra under these circumstances shows signs of 
wilting. On drying, both Species have a glistening appearance, due to a 
thin coating of mucilaginous matter, which probably assists in preventing 
excessive transpiration. 
Ulva Association, 
Rangitoto.—On the north coast of Rangitoto is a small pool separated 
from the sea by a shingle-bank. Into this the sea must penetrate, for 1t 
Porphyra Association, 
Cook Strait—aAt Lyall Bay there is a well-marked association d 
Porphyra columbina, which occurs in patches, especially covering rocky 
platforms not far above the level of half-tide. In many places it grows 
18 very varied, owing to different degrees of exposure. The 
gets most protection, is dark green or brownish-green ; exposed parts jet 
reddish or pale green. Associated algae are a few plants of Ulva an 
some small filamentous red kinds. ie 
he animals occurring with Porphyra are those of the Cha p 
association, which occupies most of the mid-tide belt hereabouts. ey 
