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 



worms 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- 

 „ .. grains, etc. A few of the species are parasites, but most of 



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 



_ a few occur in fresh water. The lamp shells shown in this 



Sea-mats . ' 



alcove superficially resemble clams, hut by structure are more 



closely related to the worms and starfishes. 



Alcove S is occupied by the starfishes, the sea urchins, sea cucumbers 



and sea lilies. The starfish is the pest of the oyster beds as 



Bi _ . it feeds on oysters and destroys them in large numbers. 



Starfish _ ■ ,'.,.. 



Starfish have the power of self-mutilation, i. e. when handled 



or attacked they are able to drop off an arm anil 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 

 AIcovg 9 



. .. , kinds living in the mud and sand of the shore while others 



Annelids 



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 is a group 

 showing a section of a mud fiat on the Xew 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 

 Alcove 10 

 . . , that of all the rest of the animal and vegetable kingdoms 



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 



P showing the anatomy of the common lobster, also enlarged 



an( j 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 



