
INVERTEBRATES, DARWIN HALL 31 
Alcove 5 These are for the most part parasitic, living in the digestive 
Round- canals of mammals. The most familiar is the common 
Oras roundworm or stomach worm, Ascaris, of which an enlarged 
model is exhibited. 
The wheel animalcules comprise many exquisite and grotesque forms, 
some of which construct tubes of gelatinous substance, sand- 
ereerers grains, etc. A few of the speci I rasites, but most of 
rains, ete. A few » species are parasites, but most o 
Rotifers cd. ee roueee 2 > pce Reet: 
them live a free, active life. They are aquatic, more abundant 
in fresh water. 
The sea-mats in Alcove 7 are plant animals which lead the colonial 
form of life. The majority of the species are marine, although 
Alcove 7 
eae a few occur in fresh water. The lamp shells shown in this 
alcove superficially resemble clams, but by structure are more 
closely related :to the worms and starfishes. 
Alcove 8 is occupied by the starfishes, the sea urchins, sea cucumbers 
and sea lilies. The starfish is the pest of the oyster beds as 
Alcove 8 : ; 
Starfish it feeds on oysters and destroys them in large numbers. 
Starfish have the power of self-mutilation, i. e. when handled 
or attacked they are able to drop off an arm and later regenerate another. 
Sea urchins are an important article of food in Europe and the West Indies. 
The annelids are worms whose bodies are made up of rings or segments. 
They are inhabitants of both fresh and salt water, many 
kinds living in the mud and sand of the shore while others 
bore into wood and shells. The “houses” that these an- 
nelids build are often very beautiful and interesting. The common earth- 
worm is perhaps the most familiar of this group. In the window 1s a group 
showing a section of a mud flat on the New England coast with the variety 
of worm life found in what to the casual observer seems to be an uninhabited 
area. 
Arthropods include the familiar crabs, lobsters, insects and their relatives. 
The number of existing species in this group is greater than 
pee that of all the rest of the animal and vegetable kingdoms 
Arthropods 
together. No other group comprises so many species useful 
or harmful to man. In the case in the center of the alcove is a model 
Sr ebassans showing the anatomy of the common lobster, also enlarged 
aa models showing heads of various species of insects. On the 
Insects wall are two of the largest specimens of lobsters that have 
ever been taken. They weighed when alive thirty-one and 
thirty-four pounds respectively. The largest of the arthropods is the giant 
crab of Japan a specimen of which is placed on the wall. 
This group is second only to the arthropods in the vast number and 
Alcove 9 
Annelids 
