OBSERVATIONS ON THE FAUNA OF THE ROCK 
BEACHES AT NAHANT, MASSACHUSETTS 
By A. S. Pearse 
I Introduction 8 
II Rock Beaches 10 
1 Rocks above high tide mark 11 
2 Balanus Zone 12 
3 Ascophyllum Zone 14 
4 Fucus Zone 19 
5 Chondrus Zone 19 
6 Inter-relations of the Zones 21 
7 Characteristics of the Fauna 23 
III The Sand Beach 29 
IV The Mud Flats 31 
V Comparison of the Faunas of the different beaches 34 
VI Annotated list of species ' 
VII Bibliography 
I. INTRODUCTION 
Nahant is a peninsula which extends from the coast of Massa- 
chusetts into the Atlantic Ocean. It consists of two rock masses 
that have been “tied” to the main land by slender sandy strips, 
(fig. 1). The hard rock strata incline away from the ocean 
(fig. 2) in such a way that their erosion makes a rough wall which 
affords a favorable habitat for a very abundant fauna. Though 
the rocks are the chief point of interest at this locality, for the 
ecologist, ample opportunity is offered for comparison with other 
types of beaches, for the eastern side of the connecting strips is 
a clean sand exposed. to the full sweep of the open ocean (fig. 1,4-), 
and on the west side there are broad mud flats (fig. 1, 1J). 
This paper is an attempt to give a picture of the conditions at 
Nahant which may serve for comparison with beaches on other 
coasts. The data were gathered during the spring of 1912, though 
the writer had previously collected in this region and had a gen- 
eral familiarity with the fauna. From June 8 to 27 the writer 
was in the field daily from morning until evening. Careful notes 
8 
