INVERTFAUiATKS. MOSQllTO 41 



Arthrojxxis include the familiar crabs, lobsters, insects and their rela- 

 tives. The luiinber of existing species in this group is 



. ^, . iijreater than that of all the r("st of tJie animal and vegetable 



Arthropods '^ , xt i • 



kingdoms together. iSo other group comprises so many 



species useful or harmful to man. In the case in the center of the alcove 



is a m()(l(>l showing the anatomy of the common lol)ster, 



, , . also enlarged models showing heads of various species of 



and Insects f^ ^ i 



insects. On the 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, some of which, like that placed on the wall, have a 



spread of about ten feet. 



The mollusks form a group second only to the arthropods in the vast 



number and di^'ersity of forms which it embraces, including marine, fresh 



water and land animals. All mollusks have soft bodies but nearly all of 



them secrete a shell which in manv species is of pearly mate- 

 Alcove II t, i X I' 



Mollusks ^^^^ (mother-of-pearl). Well-known examples of this group 



are the common clam and oyster and enlarged models in the 



Model of center case show the anatomy of these species. The largest 



Q species is the huge " bear's paw" or furbelowed clam of the 



eastern seas. 



Vertebrates include the largest, most powerful and most intelligent of 



animals. This group culminates in man who still bears 



y . , . witness to his chordate ancestry in the retention of a chorda 



(cartilaginous spine), and gill clefts during embryonic life. 



Among these ancestral forms are the Ascidians, or Sea-squirts, an enlarged 



model of which is shown in the central case, while others are shown among 



the animals on the wharf-piles in the windoW' group. The models in the 



central case show the development of the egg of typical vertebrates. 



x\n exceptionally large specimen of beautiful madrepore coral is in the 

 case near the entrance, and the associations of marine life that may be 

 ^ found among the coral reefs of the Bahamas are represented 



by several small groups in the center of the hall. Certain 

 of the groups in this section of the hall illustrate various biological principles 

 associated with the name of Darwin. The variation in form, size and 

 color of the snail and the variation of the shell of the common scallop are 

 graphically shown. 



Four large models in the center of the hall show the mosquito which is 

 the agent in the spread of malaria. These models represent 

 th M 1 '1 ^^^ insect enlarged seventy-five diameters or in volume 

 Mosquito ^^^^ hundred thousand times the natural size. The mos- 



quito in its development undergoes a metamorphosis. The 

 model at the left shows the aquatic larval stage; the larvae are the "wTig- 

 glers" of our rain water barrels. The next model is the pupal stage, also 



