English: Plate X. Acantherpestes major. Attempted restoration of a specimen, not of the largest size, for which there was not room on the plate. The body is made rather too slender and not sufficiently tapering; the head, being very imperfectly known, is concealed by a drooping frond of Neuropteris Clarksoni Lesq. The specimen is represented as leaving the water in which it is still swimming by means of its hinder legs, and as creeping up the trunk of a Lepidodendron (L. vestitum, Lesq.). Upon the trunk crawls a cockroach, Etoblattina mazona Scudd., while a broken stem of a Calamites (C. Cistii Brongn.) has fallen into a clump of fern, Neuropteris Loeschii Brongn. All the figures are of the natural size, and represent species found in the nodules of Mazon Creek. The plants however, with the exception of the last, are among the rarer species. Drawn by J.S. Kingsley.