
FOSSIL FISHES 87 
In the third alcove appear rare fossils of silver sharks or Chimvroids, 
; _.— which appear to have been developed from a primitive race 
Chimeroids 1). ix 
of sharks. Curiously enough fossil egg capsules of these 
forms are sometimes preserved, and examples are here present. In neigh- 
boring cases are shown ancient lungfishes and ganoids — groups from which 
all land-living quadrupeds are believed to be descended. 
In the fourth aleove are shown the ganoid fishes which dominated the 
waters during the Age of Reptiles. They were of many 
kinds and sizes, most of them with lozenge-shaped scales of 
bone, with enamelled surface. One of the few survivors (Amia) of this 
ancient group is here shown living (in a window aquarium), to give the 
visitor a clearer idea of the fishes of the “ Middle Ages” of the world. 
In the fifth aleove are the petrified fishes of the Age of Mammals. By 
this time nearly all of the primitive fishes like sharks, lung- 
fishes and ganoids, had become extinct; and the common 
forms were bony-fishes, or teleosts, closely related to our herrings, perches, 
mackerels and daces. 
Ganoids 
Teleosts 
[Return to the South Pavilion or Hall of Mastodons and Mammoths.| 
SOUTH CENTRAL WING 
GEOLOGY AND INVERTEBRATE PALZONTOLOGY 
Turning northward at the center of the Quaternary Hall containing 
the mastodons and mammoths, the visitor enters the South Central Wing 
of the building and is in the Hall of Geology and Invertebrate Paleontology. 
At the entrance cf the hall there is a large slab of fossiliferous limestone 
from Kelleys Island in Lake Erie near Sandusky, whose surface has been 
smoothed, grooved and scratched by the stones and sand in 
the bottom of the vast moving ice sheet or glacier that covered 
the northeastern part of North America during the Glacial 
Epoch. The front of this continental glacier is now thought by most 
geologists to have retreated northward across Lake Erie from 30,000 to 
50,000 years ago. At Kelleys Island, the ice was moving from east to west. 
Just beyond the glacial groove specimen, the visitor will see an exhibit 
illustrating some of the results of an expedition which the Museum sent to 
Martinique and St. Vincent during the great volcanic eruptions of 1902- 
1903 that devastated those islands of the Lesser Antilles chain. 
A set of four relief maps shows the island of Martinique and its 
famous volcano, Mont Pelée, at three important stages of the 
Glacial 
Grooves 
Volcanic 
Bombs 
