110 GIANT FOSSIL SHARK 
very indirectly related to them; some were small, curiously encased in 
shells; others, shown in the three cases in front of the visitor, attained 
large size and were evidently formidable creatures. One of them, in 
fact, Dinichthys, shown in the middle of the gallery, was probably 
among the most destructive creatures that ever lived in the sea. Its 
jaws were so strong that it could crush a plate of bone as thick as one’s 
hand. Such an actual specimen, fractured in life and showing the 
marks of ‘‘teeth”’ is shown in a neighboring case. 
The collection is so arranged that he who makes the tour can see the 
principal kinds of fossil fishes and is able, in a measure, to outline the 
history and pedigree of the entire group. He can trace the rise and fall 
of the early plate-covered fishes; the era of the sharks which on the one 
hand supplanted the earliest fishes and were in time replaced by the more 
efficient lungfishes and ganoids; the age of ganoids when the waters were 
filled with these enamel-scaled fishes; finally the age of the bony-fishes, 
or teleosts, the multitudinous forms of to-day, the herrings, cods, perches, 
whose methods of swimming, feeding and breeding are far more efficient 
than those of any of their predecessors. 
Above the entrance are the jaws, ‘“‘models,” spreading nine feet, of a 
huge fossil shark in which the actual teeth are arranged as 
at Ee in the sharks of to-day, in the usual banks or rows—the 
Shark teeth in the hinder rows serving to replace those in front, 
nature having dealt more kindly in the matter of teeth 
with sharks than with man. Such a shark probably measured from 
seventy to ninety feet and its race may well have become extinct, when 
for various reasons the enormous volume of food necessary to support 
it could not be maintained within its range of sea. 
In the first alcove to the left, by the window, is a ‘fossil 
aquarium”’ in which a number of models of these earliest 
fishes are arranged in a group, as though alive in the sea. 
In the next alcove are the early fossil sharks which superseded the 
tribe of plated fishes just mentioned. These sharks had soft skeletons, 
simple fins and a number of other primitive features which 
lead to the belief that of all the higher fishes, and the higher 
back-boned animals therefore as well, were descended from them, their 
simpler structures becoming more complicated in many directions. In 
one of the early sharks here exhibited, impressions of soft parts such as 
muscles and gill filaments have been preserved. 
Fossil 
Aquarium 
Sharks 
In the third alcove appear rare fossils of silver sharks or Chimeeroids, 
which appear to have been developed from a primitive race 
of sharks. Curiously enough fossil egg capsules of these 
forms are sometimes preserved, and examples are here present. 
Chimeroids 
