The first fragment of a fossil fish ever found, was in a bed of sandstone near Ludlow, England, and geologists have been eagerly searching ever since for more complete specimens, and to discover, if possible, traces of fish in the earlier rocks. Finally the United States Geological Survey has found earlier fish remains in Colorado. One of the most ardent students of fossil fishes was the noble man of science, Agassiz, who even as a young lad began a valuable collection of fish fossils. When we consider how many organisms must moulder away and perish entirely, for every one which survives, we need not wonder that comparatively few fossils have been found, but should rather wonder that so many have fallen into sufficiently favorable circumstances to survive. With the next age after the upper Silurian, fish became very abundant, and in that and every age succeeding, they predominate in the waters, where the older animal forms begin to disappear. One peculiarity about the fossil fishes of the Devonian era is, that they are often found in hard, flattened, oblong concretions. When one of these lumps, like pebbles, is given a smart tap with a hammer, it splits open, and a fish or part of a fish, is found in the centre. Hugh Miller, the Scotch geologist, graphically describes in several of his works the joy with which he secured perfect specimens of fish from such pebbles. In the Devonian age fish improved in fashion, and began to wear scales. Sometimes fossil scales are found tinged with the beautiful iris-hues which they wore in the ancient waters. Sometimes in the rocks of this and the succeeding age there are found whole beds or thick strata of fish-fragments. When these beds are opened they give forth a faint odor, like decayed fish, but all the soft parts of the fish have been destroyed long ago, and merely the bones, scales, and especially the wonderful teeth remain. FOOTNOTES: [36] Nature Reader, No. 2, Lessons 37-40. [37] Nature Reader, No. 2, p. 127. [38] In the last months of 1890, fish remains were found in rocks at Cañon City, Colorado, belonging to the first Silurian series. New discoveries constantly change such statements as that in the text. [39] The dog-fish here meant is the dog-fish of the sea, well known on the Atlantic coast. The “dog-fish” of the rivers is a very different specimen. [40] Nature Reader, No. 3, Lesson 40 _ad fine_. LESSON XVIII. THE BURIED REPTILES. “_Hamlet._ Do you see yon cloud, that’s almost the shape of a camel? _Polonius._ By the mass, ’tis like a camel indeed. _Hamlet._ Methinks it is like a weasel. _Polonius._ It is backed like a weasel. _Hamlet._ Or like a whale? _Polonius._ Very like a whale.” --SHAKESPEARE, _Hamlet_.