the mouth was situated over the center of the cup. The number of bones belonging to a single individual amounted to one hundred and fifty thousand. These are found sometimes attached, forming a perfect skeleton, but more frequently separate; portions of the stems are called entro

Fig. 119.

Cyathocrinite.

chites, screw-stones, pulley-stones, and in the north of England, fairy stones and St. Cuthbert's beads. The stem of the Encrinite is circular, while that of the Pentacrinite is pentagonal. The Cyathocrinite (cup-like Encrinite) was a genus of remarkably light and elegant appearance found principally in the Silurian, Devonian and Carboniferous limestones. The Pentacrinite is exhibited in Figure 106, $209.

224. Reptiles are found in such numbers in the secondary rocks, that the period of their deposition has been called the age of reptiles, (§ 152, II.) More than thirty new genera have been added to the class by the study of the fossil forms. Reptiles were formerly described under two orders, distinguished by the presence or absence of external feet. The variety and peculiarities of the fossil species render a new arrangement of the members of the class indispensable. The classification proposed by Professor Owen is admirably adapted to its purpose, including in natural groups all known species, fossil and recent.

CLASS III, REPTILIA.

Found fossil in.

ORDER 1. Dinosauria (Land Saurians.) Oolite, Wealden.

The reptiles of the Triassic period were of the second order, Marine Saurians; of the fourth order, Lizards-the Rhynchosaurus, so called from its head resembling the beak of a bird, and the Dicynodon, having only two teeth, which were canine; and of the eighth order, Frogs.

225. Peculiar markings, bearing striking resemblance in form and relative positions to tracks made by animals in walking, have long since been observed in the rocks of this period. In 1834, an account was published of some of these observed in the Bunter Sandstein, in Saxony. They resembled the imprint made by a human hand upon any plastic substance, as represented in the adjoining figure. It was proposed to call the animal, that made the track, Cheirotherium (Cheir, the hand; therion, beast.) No bones were then identified as belonging to this animal, its existence being inferred from its tracks alone. The dimensions of the tracks are

various, and those made by the hind feet are always much larger than those of the fore feet; in some instances twice as large. The posterior extremities of the animal appear to have been larger and longer than the anterior. Some fragments of skeletons have since been found in the rock with the tracks, which enable Professor Owen to establish a genus of the Batrachian order of reptiles, including several species frequenting the sea shore at the time of deposition of the New Red Sandstone. The jaws were furnished with at least a hundred teeth on each side, diminishing in size from the middle to the extremities; in this respect resembling those of the crocodile. An outline of the animal, as restored by Professor Owen, is presented in Figure 121. As a section of a tooth exhibits, by the Fig. 121.

aid of a microscope, labyrinthine convolutions, the animal is called the Labyrinthodon. The tracks of tortoises and crustaceous animals have also been observed in these rocks, and traced in some instances twenty and thirty feet. These fossil foot-prints are called ichnolites (ichne, track; lithos, stone.)

226. Numerous remarkable tridactyle impressions have been discovered in the sandstone of the Connecticut Valley in Massachusetts, which are universally supposed to be

the tracks of biped animals imprinted on the rocks when they were in a soft, forming state. Some specimens exhibit very clearly the character of the foot, its rows of joints, claws and integuments. The best impressions are in fine shale, which is incrusted with micaceous sandstone; the surfaces of the split strata are counterparts of each other; the shales exhibiting the tracks as moulds, and the sandstone as casts in relief. The animals which made these tracks are supposed to have been birds, though none of their bones have yet been found in these strata. President Hitchcock distinguishes more than thirty species by differences in the tracks. They are of various sizes; some as small as our sparrows, while some made a track fifteen inches long, exceeding by five inches the track of the African ostrich. The length of the stride of these largest species was from four to six feet. The doubts formerly entertained respecting these Ornithicnites have been dissipated by the discovery, in the alluvial deposits of New Zealand, of the skeletons of wingless birds as large as those to which the tracks in the New Red Sandstone are assigned, (§301.) These bird tracks have been presented in Figure 69, § 126.

227. The rocks of this period seem to have been especially fitted to perpetuate impressions: the ripple marks on them are very distinct; but, what is more remarkable, their surfaces often present a pitted appearance, dotted with little hemispherical eminences or depressions which are attributed to rain-drops. These are sometimes elongated, as if the drops were driven by the wind in an oblique direction. President Hitchcock remarks, "It is a most interesting thought, that while millions of men, who have striven hard to transmit some trace of their existence to