As regards the Vertebrate animals of the period, no extinct forms of Fishes, Amphibians, or Reptiles are known to occur, but we meet with both extinct Birds and extinct Mammals.  The remains of the former are of great interest, as indicating the existence during Post-Pliocene times, at widely remote points of the southern hemisphere, of various wingless, and for the most part gigantic, Birds.  All the great wingless Birds of the order Cursores which are known as existing at the present day upon the globe, are restricted to regions which are either wholly or in great part south of the equator.  Thus the true Ostriches are African; the Rheas are South American; the Emeus are Australian; the Cassowaries are confined to Northern Australia, Papua, and the Indian Archipelago; the species of Apteryx are natives of New Zealand; and the Dodo and Solitaire (wingless, though probably not true Cursores), both of which have been exterminated within historical times, were inhabitants of the islands of Mauritius and Rodriguez, in the Indian Ocean.  In view of these facts, it is noteworthy that, so far as known, all the Cursorial Birds of the Post-Pliocene period should have been confined to the same hemisphere as that inhabited by the living representatives of the order.  It is still further interesting to notice that the extinct forms in question are only found in geographical provinces which are now, or have been within historical times, inhabited by similar types.  The greater number of the remains of these have been discovered in New Zealand, where there now live several species of the curious wingless genus Apteryx; and they have been referred by Professor Owen to several generic groups, of which Dinornis is the most important (fig. 257).  Fourteen species of Dinornis have been described by the distinguished palaeontologist just mentioned, all of them being large wingless birds of the type of the existing Ostrich, having enormously powerful hind-limbs adapted for running, but with the wings wholly rudimentary, and the breast-bone devoid of the keel or ridge which characterises this bone in all birds which fly.  The largest species is the Dinornis giganteus, one of the most gigantic of living or fossil birds, the shank (tibia) measuring a yard in length, and the total height being at least ten feet.  Another species, the Dinornis Elephantopus (fig. 257), though not standing more than about six feet in height, was of an even more ponderous construction—­“the framework of the skeleton being the most massive of any in the whole class of Birds,” whilst “the toe-bones almost rival those of the Elephant” (Owen).  The feet in Dinornis were furnished with three toes, and are of interest as presenting us with an undoubted Bird big enough to produce the largest of the foot-prints of the Triassic Sandstones of Connecticut.  New Zealand has now been so far explored, that it seems questionable if it can retain