OrnivER.— Marine Littoral Plant and Animal Communities. 511 
except those at the posterior ends are swollen. t is suggested that 
these swellings are special organs, possibly sensitive, for pushing against 
the rocks above and below, and are thus an adaptation to the fish's habit 
stone rock (Calman, Rep. Comm. Inst. Civil Eng., 1920, p. 73). A small 
Sand. 
The main character of a sandy beach, so far as the life found there 
is concerned, is its movement, caused by wave-action. Only animals 
capable of burrowing qui n exist in the surf-swept shore. Hedley 
has pointed out that the shells of sand-dwellers are solid, smooth, and 
1 inimize the 
remain with its shell at this depth below the surface and so minimize 
i i urf. But not all sand-dwelling pelecypods 
т ај On the ocean-beach near Tauranga, where 
associated with it, in numbers — great, pic spissa, a small 
species with ventricose shell roughened by concentri м 
Brittle-stars inhabiting the sand-beach are furnished with — 
long, thin arms. Amphiura aster at Timaru, and the same sem е 
species іп Rangitoto Channel, remain with their bodies buried in t i: san Ar 
a depth of 10 cm., but the tips of the arms project above the ч асе, ап 
attend to the wants of the animal below. Polychaets are rapi UN 
to dig them out soon —Á бмр : 
iving i i i ing their way along jus 
living in sandy beaches are in the habit of ploughing the 
i tly large, with its lobes reflected 
below the surface. The foot is frequently targ evel sanati =e 
very broad. ; j Saad 
ypod Pi а in Rangitoto Channel is fo uri 
t yes — eps ненен Een the valves near the anterior 
end is a large byssus posed of numerous spreading threads, to the 
e 
extreme end of each of which is fastened a grain o sand. 
