FOOT-PRINTS OF THE TRIAS. 
373 
in pairs, each pair in the same line, at intervals of fourteen 
inches from pair to pair. The large as well as the small steps 
show the great toes alternately on the right and left side; 
each step makes the print of live toes, the first, or great toe, 
being bent inward like a thumb. Though the fore and hind 
foot differ so much in size, they are nearly similar in form. 
As neither in Germany nor in England had any bones or 
teeth been met with in the same identical strata as the foot¬ 
steps, anatomists indulged, for several years, in various con¬ 
jectures respecting the mysterious animals from which they 
might have been derived. Professor Kaup suggested that 
the unknown quadruped might have been allied to the Mar- 
supialia; for in the kangaroo the first toe of the fore foot is 
in a similar manner set obliquely to the others, like a thumb, 
and the disproportion between the fore and hind feet is also 
very great. But M. Link conceived that some of the four 
species of animals of which the tracks had been found in 
Saxony might have been gigantic Batrachians^ and when it 
was afterwards inferred that the Labyrinthodon was an air- 
breathing reptile, it was conjectured by Professor Owen that 
it might be one and the same as the Cheirotherium. 
Dolomitic Conglomerate of Bristol. —Near Bristol, in Som¬ 
ersetshire, and in other counties bordering the Severn, the 
lowest strata belonging to the Triassic series consist of a 
conglomerate or breccia resting unconformably upon the 
Old Bed Sandstone, and on different members of the Car¬ 
boniferous rocks, such as the Coal Measures, Millstone Grit, 
and Mountain Limestone. This mode of superposition will 
be understood by reference to the section below Dundry Hill 
(Fig. 85, p. 130), where No. 4 is the dolomitic conglomerate. 
Such breccias may have been partly the result of the sub¬ 
aerial waste of an old land-surface which gradually sank 
down and suffered littoral denudation in proportion as it be¬ 
came submerged. The pebbles and fragments of older rocks 
which constitute the conglomerate are cemented together by 
a red or yellow base of dolomite, and in some places the en- 
crinites and other fossils derived from the Mountain Lime¬ 
stone are so detached from the parent rocks that they have 
the deceptive appearance of belonging to a fauna contempo¬ 
raneous with the dolomitic beds in which they occur. The 
imbedded fragments are both rounded and angular, some 
consisting of sandstone from the coal-measures, being of vast 
size, and weighing nearly a ton. Fractured bones and teeth 
of saurians which are truly of contemporaneous origin are 
dispersed through some parts of the breccia, and two of 
these reptiles called Thecodont saurians, named from the 
