438 MESOZOIC TIME — REPTILIAN AGE. 



with the teeth in sockets ; and the Termatosaurus of Plieninger, from the Keuper 

 of Wurteniberg. 



(c.) Turtles. — A series of tracks like fig. 663 have been observed in Germany 

 which have been referred to a Turtle, the earliest representative of the tribe. 

 The tracks form two distant parallel lines, as they should for an animal having 

 a broad shell-covered body and short legs. 



Coprolites of Reptiles are also common. Various footprints are described 

 and named in Jardine's Ichnology of Annandale. 



(d.) Mammals. — Fig. 663 A represents the side-view of a tooth of Microlestes 

 antiquus Plieninger, from the bone-breccia of Wurtemberg; A', view of crown. 

 A tooth of the same mammal has been found at Fronie, in England. Owen 

 regards the species as probably near the modern Myrmecobius and closely re- 

 lated to another extinct Marsupial genus, Plagiaulax, found in the English 

 Upper Oolite. Fig. 663 B represents the Myrmecobius fasciatus, a species of 

 Marsupial now living in Australia. 



Fossils characteristic of the subdivisions of the Trias. 



The characteristic fossils of the three subdivisions of the Trias 

 are as follow : — 



1. Lower group. — Voltzia heterophylla, Calamites Mougeoti, Placodus impressus, 

 Nothosaurus Schimperi. 



2. Middle group. — Encrinus liliiformis, Avicula t socialis (common to all the 

 groups), Myoplioria (Trigonia) vulgaris, M. lineata, Terebratida vulgaris, Cera- 

 tites nodosus, Pemphix Sueurii, Hybodus Mougeoti, Placodus (several species), 

 Nothosaurus (species differing from those of the lower group), Simosaurus, Pisto- 

 saurus. 



3. Upper group, or Keuper. — Equiseta, Calamites arenaceus, Pterophyllum J&geri, 

 Pt. longifolium, Pt. Munsteri, Estheria (Posidonia) Keuperiana, Labyrinthodon 

 giganteus, Belodon, Termatosaurus. 



The Estheria minuta ranges through all the divisions. 



IV. General Observations. 



1. American. 

 General Progress. — The following points bear upon the history of 

 this period : — 



I. The position of the rocks in linear ranges, parallel with the 

 mountains, and therefore along depressions in the surface that 

 were made when the Appalachian foldings took place. The Con- 

 necticut valley is one of the great synclinal depressions made at 

 that time. Such areas would naturally have become inlets of the 

 sea, or estuaries, river-courses, lakes, or marshes, and would have 

 received the debris of the hills brought in by streams. 



II. The absence of Radiates, the paucity of Mollusks, and the 



