766 STRATIGRAPHICAL GEOLOGY. ~ [Book VL 
still more frequently the footprints, of labyrinthodont and even of 
saurian reptiles occur in the Keuper beds—Labyrinthodon (4 species), 
Cladyodon Lloyd, Hyperodapedon, Palxosaurus, Teratosaurus, Thecodonto- 
saurus, Rhynchosaurus, and footprints of Cheirotherium. The remains of the 
small marsupial Microlestes have likewise been discovered. 
At the top of the Red Marl certain thin-bedded strata form a 
gradation upwards into the base of the Jurassic system. As their 
colours are grey and blue, and contrast with the red marls on which 
they repose conformably, they were formerly classed without hesitation 
in the Jurassic series. Egerton, however, showed that, from the 
character of their included fish remains, they had more paleontological 
affinity with the Trias than with the bias. Subsequent research, 
particularly among the Rhetic Alps and elsewhere on the Continent, 
brought to light a great series of strata of intermediate characters 
























Fic. 362.—Ruztric Fossits. 
a, Cardium rheeticum (Merian.); b, Avicula contorta (Portlock); ce, Pecten* 
valoniensis (Defrance), 
between the previously recognized Trias and Lias. These results led to 
renewed examination of the so-called beds of passage in England, which 
were found to be truly representative of the massive formations of the 
Tyrolese and Swiss Alps. They are therefore now known as Rhetic, 
(sometimes as Infra-Lias) and are usually classed as the uppermost 
member of the Trias, but offering evidence of the gradual approach of 
the physical geography and characteristic fauna and flora of the Jurassic 
eriod. . 
The Rheetic beds extend as a continuous though very thin band at the 
top of the Trias, from the coast of Yorkshire across England to Lyme 
Regis on the Dorsetshire shores. ‘They occur in scattered patches even 
up as far as Carlisle, and westwards on both sides of the Bristol Channel. 
Their thickness, on the average, is probably not more than 50 feet, 
though it rarely increases to 150 feet. They consist of thin-bedded grey 

