lis FOSSIL AQlMilLM 



In the fourth alcove iirc shown the ganoid fishes which dominated the 



_ . , waters (hu'in*; the A^e of Keptih's. They were of manv 



Ganoids i • i i ■ . . 



Kinds and si/es, most of th<'m with lozenge-shaped scales 



of hone, with enamelled surface. One of the few survivors '\4m/a" of this 

 ancient grouj) is here shown living:; "in a window aciuarium'', to give the 

 visitor a clearer idea of the fishes of the "Middle Ages" of the world. 

 In the fifth alcove are the jx'trified fishes of the Age of Mannnals. By 

 this time nearly all of the primitive fishes, like siiarks, lung- 

 fishes and ganoids, had become extinct; and the common 

 forms were bony-fishes, or teleosts. closely related to our herrings. 

 l)erches, mackerels and daces. 



[Return to the South Pavilion or Hall of Mastodons and Mammoths.] 



SOUTH CENTRAL WING 



Geology and Ixvkhtkhhate Pal.*:()xtology 



Turning northward at the center of the Quaternary Hall containing 

 the mastodons and mammoths, the visitor enters the South Central ^^ing 

 of the building and is in the Hall of Geology and Invertebrate Palaeon- 

 tology. Paheontology is the science of the ancient life of the earth; its 

 field is the stuch' of the fos.silized shells and other hard parts and the 

 various kinds of imprints left by the animals formerly inhabiting the 

 seas and lands, and i)reserved in deposits which now form our stratified 

 rocks. As normally the upper layers of a series of strata are more recent 

 than the lower, the fossils reveal the succession of life forms in the earth's 

 crust and thus are of the highest value and interest to the student of 

 historical geology. Since, however, the r(^mains of only a small ])ropor- 

 tion of the animals living at a given period are ix'rmanently i)reserved 

 in the marine, river, lake and subaerial deposits of that period, the 

 geological record of animal and plant forms is far from complete. Inas- 

 much as invertc^brate animals are far less free in their movements than 

 the vertebrate forms, they ar(^ accepted as the best determinants of the 

 geological age of a bed of rock, even when remains of both kinds are 

 found together. Inv(Tt(^brate life, too, appeared on the globe far earlier 

 than vertebrate, and remains of certain species are abundant in the 

 low'est "oldest" of our stratified rocks. 



In the alcoves of the hall is the general collection of meteoritt^s, 



which is one of the largest and most representative in this 

 Meteorites ^ - c \ ^ a 



country, contammg as it does specnnens trom about live 



hundred of the seven hundred falls and finds that are known throughout 



the world. Some of the principal features of our collection are: 



Two thousand or more individual mass(\^ from the "stone shower" 



