PISCES. 
93 
Jurassic, Fig. 100), and Protosphyrcena (Upper Cretaceous). Wall-case 
The notochord is never much replaced by vertebral bodies, Tabl ^ a se 
but to strengthen the trunk the vertebral arches are multiplied 21 . 
and very closely arranged; the powerful forked tail is sup¬ 
ported by one fan-shaped lower vertebral arch; and the snout 
Fig. 100. —Restoration of Hypsocormus insignis, scales omitted, from the 
Upper Jurassic Lithographic Stone of Bavaria ; about one-eighth nat. 
size. (After A. S. Woodward. Wall-case 13.) 
gradually becomes elongated until it is a formidable weapon 
in Protosphyrcena. The gigantic Leedsia problematica, from 
the Oxford Clay of Peterborough, seems to belong to this 
family. Its tail, mounted between Wall-cases 13-14, has a 
span of 9 feet, and probably represents a fish 30 feet in 
length. 
Sub-order 3. —Aetheospondyli. 
These fishes are ganoids resembling the Protospondyli Wall-case 
except that their vertebral rings or bodies do not appear to m 
Jl &D16-C81S0 
21 . 
Fig. 101. —Restoration of Aspidorhynchus acutirostris, from the^Upper 
Jurassic Lithographic Stone of Bavaria ; about one-eleventh nat. size. 
(After A. S. Woodward. Wall-case 14.) 
result from the fusion of once-separate crescentic pieces. 
Aspidorhynchus (Fig. 101), with constricted ring-vertebrae, 
is represented in Wall-case 14 by a fine series of specimens 
