1913 ] 
Pearse: Fauna of the Rock Beaches 
31 
The fauna of the sand beach is composed largely of burrowing 
animals and ability to penetrate the shifting substratum is often 
combined with a heavy body. However, an important part of 
this fauna consists of more or less pelagic animals which frequent 
the shore water or come in from open ocean. The pelagic species 
are the same for the most part as those found on the rock beaches. 
Fig. 27. Polyneces heros ( x ) Burrowing in the Sand After Being Left 
by the Side. 
Some excavated sand has been removed to show the snail. 
IV. THE MUD FLATS 
The mud flats at Station 14 (fig. 1) showed a gradual transition 
from rather clean sand at the top to soft black mud in the deeper 
parts. A few r boulders and stones w r ere scattered all through, 
except in the softest mud. Five zones (fig. 28) were distinguished 
but they were much less sharply marked than those on the rocks 
or sand beaches. They were as follows: 
Fig. 28. Section of Mud Beach at Station 14 (Fig. 1) Showing Zones. 
1. It was noticeable that the rocks and boulders at the top 
of the beach were bare of algae. A few stunted tufts of Asco- 
phyllum occasionally appeared; Fucus was wholly lacking (fig. 29). 
The ubiquitous barnacles and Littorina litorea were abundant on 
the rocks, and Carcinides maenas hunted among the stones. 
