The Trias then seems to mark the boundary between the fourth and fifth days. The fourth day seems to have been on the earth a period of great change, not only in physical conditions, but also in the forms of life. In the latter point of view, however, it seems to have been marked by the passing-away of old forms much more than by the origination of new ones, and hence the barrenness of the Geological Records is in exact accordance with the silence of the Mosaic Record as to any new developments. SECTION 8. THE FIFTH DAY "And God said. Let the waters swarm swarms, the soul of life, and let fowl fly above the earth in the face of the firmament of heaven. "And God created the monsters, the great ones, and every soul of life that creepeth, with which the waters swarmed, after their kind, and every winged fowl after his kind; and God saw that it was good. "And God blessed them, saying, Be fruitful and multiply, and fill the waters in the sea, and let fowl multiply on the earth. "And there was evening, and there was morning, a fifth day." The fifth and sixth days of Creation are those to which the theory of development chiefly refers. It will, therefore, be better to defer the consideration of its bearing on the narrative till the relation of that narrative to Geological facts has been considered, since it can only be thoroughly weighed when taken in connexion with the facts which belong to the two days. The beginning of the fifth day may be assigned to a point near where the Trias is succeeded by the Lias. As the Trias is drawing to its close, the class of reptiles, whose first known appearance belongs to the carboniferous epoch of the third day, begins to show signs of advance. The first true Saurians are found in the Trias: the great development takes place in the Lias and Oolite, while in the chalk large quantities of kindred remains are found, which, however, are not identical with the species found in the earlier groups. Of these some were probably almost entirely aquatic, as their limbs take the form of paddles; others were purely terrestrial, a large proportion were amphibious, and some, as the pterodactylus, bore the same relation to the rest of their class as the bats bear to the other mammalia, being furnished with membranous wings, supported upon a special development of the anterior limbs. One important characteristic of the race at this time was the great size of many of its members: thirty feet is by no means an uncommon length. This marks the fitness of the name given to the class by Moses.