Some marsupial Mammals have left their remains in the Upper Oolite as in the Lower. They belong to the genus _Sphalacotherium_. Besides the Plesiosauri and Teleosauri, there still lived in the maritime regions a Crocodile, the _Macrorhynchus_; and the monstrous _Pœcilopleuron_, with sharp cutting teeth, one of the most formidable animals of this epoch; the _Hylæosaurus_, _Cetiosaurus_, _Stenosaurus_, and _Streptospondylus_, and among the Turtles, the _Emys_ and _Platemys_. As in the Lower Oolite, so also in the Upper, Insects similar to those by which we are surrounded, pursued their flight in the meadows and hovered over the surface of the water. Of these, however, too little is known for us to give any very precise indication on the subject of their special organisation. The most remarkable fact relating to this period is the appearance of the first bird. Hitherto the Mammals, and of these only imperfectly-organised species, namely, the Marsupials, have alone appeared. It is interesting to witness birds appearing immediately after. In the quarries of lithographic stone at Solenhofen, the remains of a bird, with feet and feathers, have been found, but without the head. These curious remains are represented in Fig. 122, in the position in which they were discovered. The bird is usually designated the Bird of Solenhofen. [Illustration: Fig. 123. Shell of Physa fontinalis.] The Oolitic seas of this series contained Fishes belonging to the genera _Asteracanthus_, _Strephodes_, _Lepidotus_, and _Microdon_. The Cephalopodous Mollusca were not numerous, the predominating genera belonging to the Lamellibranchs and to the Gasteropods, which lived on the shore. The reef-making Madrepores or Corals were more numerous. A few Zoophytes in the fossil state testify to the existence of these extraordinary animals. The fossils characteristic of the fauna of the period include _Ammonites decipiens_ and _A. giganteus_, _Natica elegans_ and _hemispherica_, _Ostrea deltoidea_ and _O. virgula_, _Trigonia gibbosa_, _Pholadomya multicostata_ and _P. acuticostata_, _Terebratula subsella_, and _Hemicidaris Purbeckensis_. Some _Fishes_, _Turtles_, _Paludina_, _Physa_ (Fig. 123), _Unio_, _Planorbis_ (Fig. 201), and the little crustacean bivalves, the Cypris, constituted the fresh-water fauna of the period. The terrestrial flora of the period consisted of Ferns, Cycadeaceæ, and Conifers; in the ponds and swamps some Zosteræ. The _Zosteræ_ are monocotyledonous plants of the family of the Naïdaceæ, which grow in the sandy mud of maritime regions, forming there, with their long, narrow, and ribbon-like leaves, vast prairies of the most beautiful green. At low tides these masses of verdure appear somewhat exposed. They would form a retreat for a great number of marine animals, and afford nourishment to others. * * * * * [Illustration: XX.--Ideal Landscape of the Upper Oolitic Period.]