i.w i:i:'i j:jih'.\ri':s, \\i.\i)if\\ ch'oi rs 45 



exposes the worms wilhiii the l)Ui-i-«)\\ s. Se\-er;il species of these are 

 represented. 



In tlie Molhisk Ah-oxc window is shown the n.-ituial history- of a 

 sand-spit at ('old Sprinij; Ilarhoi', Lon«;" Ishmd. inehKhn^ some of ihe 



sliore molhisks and theii" associates. The eiiti;ince of 

 ^^^ tlie hai-l)or is seen in tlie (hstanco. In the fore<;i-ound 



Qj.Q^ at the e(l<»;e of the sand-si)it a nnissel-lx'd is exi)osed hy the 



reeechng tide over wliich fi(hller-('ral)s are swarming" into 

 their l)urrows. l^eneatli the water surface an oyster is l)ein<»; attacked 

 by a star-fish, whih' crabs and molhisks of various species are i)ui'suin,t2,' 

 their usual activities. 



The A\andow group in the X'ertebrate Alcove shows the j)iles of 



an old wharf at Mneyard Haven, Mass. l^elow the low- 

 ^ ^ ^ ^ tide mark the submerged piles are covered with fiower- 



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 cartila- 

 ginous spine. x\t first they are free swimming but later in life many of their 

 organs degenerate and they become fitted to a stationary mode of life. 

 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 



ana ion domesticated fowls, the wild species from which they have 



Under , i • , i • i • • , r -, 



Domestication ^^^^^ derived being shown m company with some of the 



more striking breeds derived from them. 

 On the right, various exhibits will show variation in nature. 

 An example of this is the variation among the finches 

 ana ion ^^ ^-^^ genus Geospiza in the Galapagos Islands. 



Other examples show' by means of a series of mollusks 



the range of color variation within a single species of AVest Indian 



Sun Shell, variation of sculpture wdthin a single genus of land snail, 



and oscillation of variations about the normal type of the common scallop. 



The struggle for existence is portrayed by the meadow mouse, 



surrounded by its many enemies and yet continuing 



rugg e or ^^ maintain an existence by virtue of its great birth rate. 



The simpler features of the laws of Heredity as eluci- 

 dated by Mendel and his followers are illustrated by the inheritance 



„ ,.^ of seed-coat color in the common pea, the color of sweet 



Heredity , . ■ c 



peas, and the coat-color of rats as shown m a series of 



panels in the neighboring case. 



[Return to the elevators.] 



