AMPHIBIA. 
47 
Sub-order 1.—Labyrinthodontia. 
The largest and most typical Stegocephalia possess power¬ 
ful conical teeth, which are curiously complicated in structure. 
Each tooth is a hollow cone, with the wall folded inwards in 
numerous vertical pleats, which are crumpled where crushed 
together. In allusion to this peculiarity, which is well shown 
by a tooth of Mastodonsaurus in Table-case Y, the animals 
are named Labyrinthodontia (“ labyrinth-toothed ”). 
The largest Labyrinthodonts are those from the Upper 
Fig. 43.—Skull of Mastodonsaurus giganteus, upper view with sculpture 
omitted, from the Lower Keuper of Wurtemberg; about one-eighth nat. 
size. Ep. lateral supratemporal; Fr. frontal; Ju. jugal; L. lachrymal; 
Mx. maxilla; Na. nasal; P. parietal; Pr.f. prefrontal; Pt. postfrontal; 
Pt.o. postorbital; Q.J. quadratojugal; S.T. prosquamosal; S.Oc. inner 
supratemporal; Sg. squamosal. The double lines indicate slime- 
canals. (After E. Fraas.) 
Trias of Wurtemberg referred to Mastodonsaurus. The skull 
of M. giganteus (Fig. 43) sometimes measures 4 feet in length. 
A plaster cast of a smaller skull is exhibited in Wall-case 
19, and fragments of actual bones and teeth of the same 
genus are placed in Table-case Y. Capitosaurus is another 
well-known Triassic genus, comprising species of smaller 
size, represented in Wall-case 19, not only by skulls from 
Germany, but also by a well-preserved skull from the Keuper 
Sandstone of Stanton, near Uttoxeter, North Staffordshire. 
Wall-ease 
19. 
Table-case 
V. 
