246 THE AMERICAN MUSEUM JOURNAL 



of the particular community, made possible through the fourth and fifth 

 principles — namely, that no two animals are exactly alike in the same or 

 successive generations and may differ greatly from one generation to the 

 next, and that the differences of the surviving animals tend to be inherited 

 by their offspring. The net result of these principles shows that the true 

 unit in animal life is not the individual, but the individual with its animate 

 and inanimate environment. 



Thus it will be seen that a museum group representing as in life a natural 

 association of animals will necessarily illustrate within itself all those laws 

 which lie at the basis of the doctrine of evolution, to the presentation of 

 which the Darwin hall is dedicated. 



The most recently installed of these groups shows the animals of a 

 portion of the sea bottom of our Atlantic coast where the conditions of life 

 are favorable to the existence of those curious forms, the marine worms. 

 These animals are particularly suited to illustrate the principles of evolu- 

 tion, because of their diversity of form and habits, and their close adapta- 

 tion to their surroundings. 



The locality chosen for the setting is the Greater Harbor of Woods Hole, 

 Massachusetts. In the upper part of the group, a distant view of the 

 wharves and buildings of the United States Fish Commission is shown on a 

 colored, photographic glass transparency six feet in length. In the middle 

 distance, on a similar transparency, is the grass-covered spur of Devil's 

 Foot, a small island at the harbor entrance. In the cove sheltered by the 

 island and its projecting spur, the tides have deposited their load of silt 

 washed from neighboring points to form a muddy bottom. 



Below the surface of the water, which is here represented as if in section, 

 the border of an extensive patch of eel grass growing in the mud is shown to 

 the left and is continued into the transparent background. Here is seen 

 the animal life to which such conditions are favorable. Lurking at the 

 edge of the eel-grass is a green crab, while just beyond its reach, mud 

 minnows are nibbling at the seaweed. A whelk crawls over the sand 

 searching for the clams and other bivalves which form its food. A scallop 

 disturbed by their maneuvers "jumps" in its awkward flopping fashion 

 into the eel-grass. Hermit crabs, mud snails and shrimp are busily ful- 

 filling their duty as the street-cleaning department of the shallow waters, 

 while mud crabs hide in every crevice. 



Finally below this zone of shallow-water life, there is shown still another 

 world composed of dwellers beneath the sea bottom itself. These are the 

 marine worms. Burrowing in the mud below the eel grass, tunneling in 

 the sandy mud of the open spaces or in the still more sandy stretches where 

 the bottom slopes up toward the pebble-strewn sea-margin, is this under- 

 world of creatures, strange in form and habits, often magnificently clad in 

 armor of iridescent coloring, adorned with breathing plumes and grotesque 



