FOSSIL EEMAINS OF LABYRINTHODON. 
371 
mensions in comparison with any representatives of that 
order now living. Both the Continental and English fossil 
teeth exhibited a most complicated texture, dilfering from 
that previously observed in any reptile, whether recent or 
extinct, but most nearly analogous to the Ichthyosaurus, 
A section of one of these teeth exhibits a series of irregular 
folds, resembling the labyrinthic windings of the surface of 
the brain; and from this character Professor Owen has pro¬ 
posed the name Labyrinthodon for the new genus. The an¬ 
nexed representation (Fig. 393) of part of one is given from 
Fig. 393 '. 
a. Pulp cavity, from which the processes of pulp and dentine radiate. 
his “ Odontography,” plate 64, A. The entire length of this 
tooth is supposed to have been about three inches and a half, 
and the breadth at the base one inch and a half. 
lock-salt .—In Cheshire and Lancashire there are red clays 
containing gypsum and salt of the age of the Trias which 
are between 1000 and 1500 feet thick. In some places len¬ 
ticular masses of pure rock-salt nearly 100 feet thick are in¬ 
terpolated between the argillaceous beds. At the base of 
the formation beneath the rock-salt occur the Lower Sand¬ 
stones and Marl, called provincially in Cheshire “ water- 
stones,” which are largely quarried for building. They are 
often ripple-marked, and are impressed with numerous foot¬ 
prints of reptiles. 
The basement beds of the Keuper rest with a slight un- 
