530 Transactions. 
rocks. The tunicates Corella and Styela caerulea are examples. Under 
stones in rock-pools Corella is the dominant member of an association which 
includes many other fixed animals, such as sponges, tubicolous worms, 
are Haliotis iris, Scutus ambiguus, Astraea sulcata, Evechinus chloroticus, 
Tugalia intermedia, and Anomia walteri with thin shells bearing polyzoa 
and Spirorbis. (Plate 47, fig. 2.) 
Cynthia Association. 
Spirits Bay.—This is the only surf tunicate formation that I have come 
across in New Zealand. It occupies exposed sloping rocks between tides 
and above the brown-algae formation. A large species of Cynthia, allied 
to C. praeputialis of Australia, grows closely together and completely 
cR à 
attached by means of a byssus passing through a narrow opening between 
the valves (Mytilus). There are associations in which the dominant animals 
d i бе 
i ), or on ute forr of vegetable life (Cellana). . Active 
animal- and vegetable-feeders are only subsidiary life-forms in this form- 
tion. | 
_ According to the dominant growth-form, four subformations may be 
distinguished, and in each of these one or more associations are recognized. 
The four subformations are sessile cirripede, pelecypod, tubicolous poly- 
chaet, and gasteropod. 
