The name of _Thylacotherium_, or _Amphitherium_, or _Phascolotherium_, is given to the first of these marsupial Mammals which made their appearance, whose remains have been discovered in the Lower Oolite, and in one of its higher stages, namely, that called the _Great Oolite_. Fig. 110 represents the jaw of the first of these animals, and Fig. 111 the other--both of the natural size. These jaw-bones represent all that has been found belonging to these early marsupial animals; and Baron Cuvier and Professor Owen have both decided as to their origin. The first was found in the Stonesfield quarries. The Phascolotherium, also a Stonesfield fossil, was the ornament of Mr. Broderip’s collection. The animals which lived on the land during the Lower Oolitic period would be nearly the same with those of the Liassic. The insects were, perhaps, more numerous. The marine fauna included Reptiles, Fishes, Molluscs, and Zoophytes. Among the first were the Pterodactyle, and a great Saurian, the Teleosaurus, belonging to a family which made its appearance in this age, and which reappears in the following epoch. Among the Fishes, the Ganoids and Ophiopsis predominate. Among the Ammonites, _Ammonites Humphriesianus_, _A. Herveyii_ (Fig. 112), _A. Brongniarti_, _Nautilus lineatus_, and many other representatives of the cephalopodous Mollusca. Among the Brachiopods are _Terebratula digona_ (Fig. 113) and _T. spinosa_. Among the Gasteropoda the _Pleurotomaria conoidea_ is remarkable from its elegant shape and markings, and very unlike any of the living _Pleurotoma_ as represented by _P. Babylonia_ (Fig. 114). _Ostrea Marshii_ and _Lima proboscidea_, which belong to the Acephala, are fossil Mollusca of this epoch, to which also belong _Entalophora cellarioides_, _Eschara Ranviliana_, _Bidiastopora cervicornis_; elegant and characteristic molluscous Polyzoa. We give a representation of two living species, as exhibiting the form of these curious beings. (Figs. 115 and 116.) [Illustration: Fig. 112.--Ammonites Herveyii.] [Illustration: Fig. 113.--Terebratula digona.] [Illustration: Fig. 114.--Pleurotoma Babylonia. (Recent.)] The Echinoderms and Polyps appear in great numbers in the deposits of the Lower Oolite: _Apiocrinus elegans_, _Hyboclypus gibberulus_, _Dysaster Endesii_ represent the first; _Montlivaltia caryophyllata_, _Anabacia orbulites_, _Cryptocœnia bacciformis_, and _Eunomia radiata_ represent the second. [Illustration: Fig. 115.--Adeona folifera. (Recent Polyzoa.)] [Illustration: Fig. 116.--Cellaria loriculata. (Recent Polyzoa.)]