OLIVER.— Marine Littoral Plant and Animal Communities. 513 
shell is composed of eight overlapping valves set in a leathery girdle. 
Species living in the most exposed situations are Sypharochiton pellis- 
serpentis, Plaxiphora biramosa, P. oblecta, P. caelata, and Eudoxochiton 
nobilis: a depressed form is characteristic of all these. 
c.) Thyrostraca.—Among the commonest and most exposed animals in 
y 
(d.) Fishes.— Species of the family Gobiesocidae are surf-fishes admirably 
adapted to their station—firstly, by a broad ventral sucker formed from the 
modified pelvic and pectoral fins, and, secondly, by their depressed form. 
Head on to the waves, Diplocrepis puniceus would offer as little resistance 
as a limpet. M 
(е.) Stelleroidea.— The only echinoderms commonly exposing themselves 
to the surf are the starfishes Patiriella regularis and Stichaster australis. 
Patiriella is pentagonal in form, and depressed. The edge of the disc being 
close to the rock, this species remains in perfect security while the sea 
passes over it. Stichaster is a many-rayed form that is capable of sticking 
to the rock so firmly that a considerable amount of force is required to 
dislodge it. 
( Dn Pelecypoda.—Ostrea cucullata in exposed places has the whole of 
the outside of the left valve cemented to the rock; the right valve is but 
little arched, so that the waves sweep harmlessly by. Mytilus and M odiolus 
common about low-tide mark from à 
grows among large brown algae, swaying to and fro with rag e den 
composed of a tough leathery integument, is 6-8 тт. in diameter = 
50cm. or more in length. The stalked cirripedes Scalpellum villosum an 
luded in the present ie though 
1 refer the protection of rock-crevices. 
pierde ck, pliant stems. These are by no 
off during storms it is usually the 
It is only necessary to 
of Durvillea antarctica and Eclonia 
mention the thick but pliant stems Ca 
Richardsoni the thinner and very tough stems of Marginaria, 
Phyllum, téphophoris and Lessonia, and the extremely long rope-like stems 
f ; ) ` ; LI LJ LI 
н миа А form of the leaf or thallus is characteristic 
of most marine plants, the degree of dissection varying with the movement — 
17—Trans. 
