10 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [304] 
up another zone which is ordinarily only washed by the waves and spray, 
but is in part occasionally covered by unusually high tides. As the 
tides do not rise very high in this region these zones are all much uar- 
rower and less distinctly marked than on the coast further north, and 
especially on the coast of Maine and in the Bay of Fundy, but yet they 
can always be easily recognized and distinguished by their peculiar forms 
of animal and vegetable life. Pools of sea-water left by the tide fre- 
quently occur in each of these zones, among the rocks, and afford 
excellent opportunities tor studying and collecting the animals. 
The animals of rocky shores are to be sought for in a variety of ways. 
A few occur quite exposed, clinging to the rocks or weeds, in defiance of 
the surf. These are chiefly univalve shells, barnacles, and such animals 
as grow like plants, firmly attached to solid objects, among these are 
the bryozoa, hydroids, and sponges. A much larger number seek shel- 
ter under the rocks, or on their lower sides, or in crevices and cavities 
between them; these must be sought by turning over the rocks and ex- 
ploring the crevices concealed by the Fucus, &c. Many other species 
conceal themselves still more effectually by burrowing in the mud, 
gravel, and sand beneath and between the rocks; these are often 
uncovered in turning over the rocks, but must also be sought for 
by digging with a spade, stout trowel, or some other tool, in the 
dirt exposed when the rocks are removed. The number of curious 
species of annelids, holothurians, bivalve-shells, actinia, &c., which 
can be unearthed in this way is always very surprising to the inexpe- 
rienced in this kind of collecting. Still other kinds can be found by 
carefully examining the pools and discovering the smaller animals by 
their motions, or by the shadows that they cast when the sun shines, 
or by noticing their burrows, or, if time will not admit of a more care- 
ful examination, by sweeping a fine hand-net through the weeds along 
the edges. Many small crustacea, shells, etc., may also be found cling- 
jong to the corallines and other alge growing in such pools, or even 
among the alge lying upon the rocks, and especially among masses of 
detached alge, thrown up by the waves. 
In the uppermost zone the animals are of comparatively few kinds, 
but these usually occur in great abundance. The most conspicuous is, 
perhaps, the common “ rock-barnacle” or ‘ acorn-shell,” Balanus bal- 
anoides, which adheres firmly to the rocks by its base and can resist 
the most violent surf, even on the outer ocean shores. When left by 
the tide these dull white conical shells are not calculated to attract 
much attention, except on account of their vast numbers, for they 
sometimes completely whiten the rocks for long distances along the 
zone in which they flourish best, and even so crowd against each other 
that they cannot assume their normal form, but become greatly elon- 
gated. But when the tide comes in, each one lifts up the double-door 
which closes the aperture at the summit of the shell and puts out an 
organ, bearing a cluster of gracefully curved and fringed arms, which 
