
INVERTEBRATES. WINDOW GROUPS 33 
exposes the worms within the burrows. Several species of these are 
represented. 
In the Mollusk Alcove window is shown the natural history of a 
sand-spit at Cold Spring Harbor, Long Island, including some of the 
shore mollusks and their associates. The entrance of 
aa a the harbor is seen in the distance. In the foreground 
Group at the edge of the sand-spit a mussel-bed is exposed by the 
receding tide over which fiddler-crabs are swarming into 
their burrows. Beneath the water surface an oyster is being attacked 
by a star-fish, while crabs and mollusks of various species are pursuing 
their usual activities. 
The window group in the Vertebrate Alcove shows the piles of 
an old wharf at Vineyard Haven, Mass. Below the low- 
tide mark the submerged piles are covered with flower- 
like colonies of invertebrate animals. Among these 
are sea-anemones, tube-building worms, hydroids, mussels, seamats and 
several kinds of ascidians or sea-squirts. The latter are primitive 
members of the Chordate group which includes the vertebrates. Like 
the embryo of man, they possess during their larval period a chorda or 
cartilaginous spine. At first they are free swimming but later in life 
many of their organs degenerate and they become fitted to a stationary 
mode of life. 
Wharf Pile 
Group 
In the northeast corner of the Hall, a window group shows the animals 
and plants of a rock tide-pool, the ‘‘ Agassiz Cave,” at Nahant, Mass. 
Under a natural bridge below a 60-foot cliff the falling 
ae tide leaves a pool in a _ rocky basin, sheltered within 
Group which is a community of sea-anemones, sea-stars, corals, 
sponges, hydroids and other animals living in the midst of 
a gorgeous sea-garden of marine plants such as are common on the 
northern New England coast. Through the arch of the natural bridge 
may be seen a curious rock formation known as the “Pulpit Rock.”’ 
Other exhibits illustrate certain facts made clear by Darwin, and 
those who came after him. On the left facing the entrance variation 
under domestication is illustrated by dogs, pigeons, and 
i rg domesticated fowls, the wild species from which they have 
Domestication been derived being shown in company with some of the 
more striking breeds derived from them. 
On the right, various exhibits will show variation in nature. 
Variation An example of this is the variation among the finches 
in Nature of the genus Geospiza in the Galapagos Islands. 
