The oldest air breathers at present known are Scorpions and insects allied to the modern May-flies, which have been found in the Silurian. Next to these, and more important in number and variety, are the insects of the Erian plant beds of New Brunswick. They were discovered by the late lamented Prof. C. F. Hartt in the plant-bearing shales of the Middle Devonian (Fig. 123). The beds containing them hold also a species of _Eurypterus_, an obscure Trilobite, and a Crustacean allied to the modern Stomapods,[42] besides a shell which may possibly be that of a Land-snail, to be mentioned in the sequel. They are also exceedingly rich in beautifully-preserved remains of Devonian plants. The collection made by Prof. Hartt is limited to a few fragments of wings; but these, in the skilful hands of Mr. Scudder, have proved to be rich in geological interest. One is a gigantic _Ephemera_ or May-fly, which must have been five inches in the expanse of the wings, which are more complex in their venation than those of its modern allies (Fig. 123, _a_). Another presents peculiarities between those of the May-flies and Dragon-flies (Fig. 123, _b_). A third is a Neuropter, not belonging to any known family, but allied to some in the Coal-formation (Fig. 123, _c_). A fourth (Fig. 123, _d_) is a small and delicate wing, supposed to have belonged to an animal having some points of resemblance to the modern crickets. Two others are represented by mere fragments of wings, insufficient to determine their affinities with certainty. No other insects of this age have been discovered elsewhere; but it is to be borne in mind that no other locality rich in Devonian plants has probably been so thoroughly explored. The hard slaty ridges containing these fossils are well exposed on the coast near the city of St. John, and Messrs. Hartt and Matthew of that city, acting, I believe, in concert with and aided by the Natural History Society of the place, not only searched superficially, but removed by blasting large portions of the richest beds, and examined every fragment with the greatest care. Their primary object was fossil plants, of which they obtained magnificent collections; and it is scarcely possible that the insects could have been found but for the exhaustive methods of exploration employed. It is interesting to observe, respecting these oldest insects, that they all belong to those families which have jaws, and not suctorial apparatus, that they are not of those which undergo a complete metamorphosis, and that their modern congeners pass their larval stage in the water. Thus the waters gave birth to the first insects, and their earliest families were not of those which suck honied juices or the blood of animals, or which pass through a worm-like infancy. These groups belong apparently to much later times.