so striking a feature of the Carboniferous, is to be noticed as an important fact for the Evolutionist, the Cycadae and Coniferae completely replacing them. Among the Batrachia of the Trias are to be noticed the immense Labyrinthodons, the skull in one species measuring three feet long by two wide; remains of these animals have been found near Gwynedd, in the Triassic of Pennsylvania. The Connecticut Sandstone is famous for its tracks, supposed to have been made by large Reptiles, of which more than fifty species have been described. During this period the Birds first appeared, and, from their tracks left in the sandstone, they are thought to have resembled the Running-birds of the present day, though much larger, the Brontozoon (Fig. 148) of the Connecticut valley being four times as large as the Ostrich. The existence of such large birds may be doubted by those who are not familiar with fossils. Those, however, who have seen the gigantic Dinornis of the British Museum are quite satisfied with Prof. Owen's statement, that they are "equal to the formation of tridactyle impressions as large as those of the Connecticut Sandstones." (Pal., p. 331.) In the Triassic the remains of Mammals are first found. The fossil remains Microlestes and Dromatherium (Fig. 149) are usually regarded as Marsupials, or pouch-bearing Mammalia. The Dromatherium, according to Prof. Owen, "would appear to find its nearest analogue in the Myrmecobius," a little Marsupial living at the present day in Australia. These fossil Mammals have been supposed by some authors to be Monotremata, though that order have no teeth, as in the Duck-bill, etc. This perhaps, however, was not the primitive condition of the order, the first Monotremata having teeth, which their descendants have lost through adaptation to their peculiar mode of life. Whether this view be or be not confirmed by future research, the important fact to be noticed is that in either case the Mammals which first appeared on the earth were
