Murchison, De Verneuil, and
     Von Keyserling.
 (3) ‘Siluria,’ Murchison.
 (4) ‘Permische System in Sachsen.’  Geinitz and Gutbier.
 (5) ‘Die Versteinerungen des Deutschen Zechsteingebirges,’ Geinitz.
 (6) ‘Die Animalischen Ueberreste der Dyas.’  Geinitz.
 (7) ‘Monograph of the Permian Fossils of England’ (Palaeontographical
     Society).  King.
 (8) ‘Monograph of the Permian Brachiopoda of Britain’
     (Palaeontographical Society).  Davidson.
 (9) “On the Permian Rocks of the North-West of England and their
     Extension into Scotland”—­’Quart.  Journ.  Geol.  Soc.,’ vol. xx. 
     Murchison and Harkness.
(10) ’Catalogue of the Fossils of the Permian System of the Counties
     of Northumberland and Durham.’  Howse.
(11) ‘Petrefacta Germaniae.’  Goldfuss.
(12) ‘Beitraege zur Petrefaktenkunde.’  Munster.
(13) ‘Ein Beitrag zur Palaeontologie des Deutschen Zechsteingebirges.’ 
     Von Schauroth.
(14) ‘Saurier aus dem Kupfer-schiefer der Zechstein-formation.’  Von
     Meyer.
(15) ‘Manual of Palaeontology.’  Owen.
(16) ‘Recherches sur les Poissons Fossiles.’  Agassiz.
(17) ‘Ichnology of Annandale.’  Sir William Jardine.
(18) ‘Die Fossile Flora der Permischen Formation.’  Goeppert. (19) ‘Genera et Species Plantarum Fossilium.’  Unger. (20) “On the Red Rocks of England of older Date than the Trias”
     —­’Quart.  Journ.  Geol.  Soc.,’ vol. xxvii.  Ramsay.

CHAPTER XV.

THE TRIASSIC PERIOD.

We come now to the consideration of the great Mesozoic, or Secondary series of formations, consisting, in ascending order, of the Triassic, Jurassic, and Cretaceous systems.  The Triassic group forms the base of the Mesozoic series, and corresponds with the higher portion of the New Red Sandstone of the older geologists.  Like the Permian rocks, and as implied by its name, the Trias admits of a subdivision into three groups—­a Lower, Middle, and Upper Trias.  Of these sub-divisions the middle one is wanting in Britain; and all have received German names, being more largely and typically developed in Germany than in any other country.  Thus, the Lower Trias is known as the Bunter Sandstein; the Middle Trias is called the Muschelkalk; and the Upper Trias is known as the Keuper.

I. The lowest division of the Trias is known as the Bunter Sandstein (the Gres bigarre of the French), from the generally variegated colours of the beds which compose it (German, bunt, variegated).  The Bunter Sandstein of the continent of Europe consists of red and white sandstones, with red clays, and thin limestones, the whole attaining a thickness of about 1500 feet.  The term “marl” is very generally employed to designate the clays of the Lower and Upper Trias; but the term is inappropriate, as they may contain no lime, and are therefore not always genuine marls.  In Britain the Bunter Sandstein consists of red and mottled sandstones, with unconsolidated conglomerates, or “pebble-beds,” the whole having a thickness of 1000 to 2000 feet.  The Bunter Sandstein, as a rule, is very barren of fossils.