40 iw inrri'.HHAriis. wisixnv anoirs 



hodics. hut nearly all ol lliciii secrete a shell which in many 

 Alcove II siH'cies is ol' jx-arly material (mother-of-pearl). Well- 



Mollusks known exanii)l(*s of this ^rouj) are the connnon clam and 



Model of oyster and enlarged models in the center case show the 



Clam and anatoniN" of these species. The largest species is the huge 



^^ ^^ "hear's ])aw" or furhe.lowed clam of the eastern seas. 



N'ertehrates include the lar<!;est. most powerful and most intelligent of 



animals. This grou]) 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 en- 

 larged model (jf 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 ty])ical verte- 

 brates. 



An exceptionally large s})ecimen of beautiful madre])(jre coral is in the 

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



found among the coral reefs of the Bahamas are repre- 

 Coral sented by several small groups in the center of the hall. 



Certain of the groups in this section of the hall illustrate 

 various l)iological i)rinciples associated with the name of Darwin. The 

 variation in form, size and color of the snail and the variation of the shell 

 of the connnon scallop are graphically shown. 



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



the cause of the spread of malaria. These models represent 

 Models of ^Y^^ insect enlarged seventy-five diameters or in volume 



tllG IVl3.l3.ri3.1 *^ . 



T., .^ four lumdred thousand times the natural size. The mos- 



Mosquito 



quito in its development undergoes a metamorphosis. The 



model at the left shoAvs the aquatic larval stage; the larvae are the 



'Svrigglers" of our rain w^ater barrels. The next model is the pupal 



stage, also aquatic. The third model is of the adult male mosquito 



which is harmless since it never l)ites man. The fourth model shows the 



adult female moscjuito in th(^ attitude of biting. In another case is a 



series of models showing the life cycle of the malarial germ in the blood 



of man and in the mosquito. 



In several of the alcove windows are habitat gr()ui)s of invertebrates 



illustrating tlu* natural historv of the commoner and more 

 Window ^11 



^ t\'])ical annuals. 



Groups • ' 



In the Annulate Alcove is shown the Marine Worm 

 (Irouj) re])r()ducing these animals with their as.sociates in their natural 

 surroundings, as secui in the harbor of Woods Hole, Mass. The 

 harbor and the distant view of Woods Hole village with the U. S. 

 Fish Conunission buildings are shown in the l)ackground. rei)resented 



