From the point of view of the determination of the habitat, we come now to the most significant occurrence of eurypterids thus far known in the British Isles. To be sure the "seraphims" of the Old Red Sandstone discovered by the stone-cutter of Cromarty and proclaimed by Agassiz to be "the remains of a huge lobster," are deservedly famous. Their size, abundance, association with the monster cephalaspid fishes, and above all the mystery attending their place in nature have shed upon the eurypterids of the Old Red Sandstone a picturesque and historical glow which makes the later discoveries of faunas merely so many cold triumphs of science. But the light which the Devonic merostomes throw upon the solution of the problem of the habitat cannot compare with that which emanates from the fauna of the Wenlock. And the reason is this: A large number of geologists have already come to the conclusion that the Old Red Sandstone was a series of torrential and flood plain deposits, in which case they can hardly fail to believe that the organisms found in the deposits were river-dwellers. Furthermore, it will not be a very difficult undertaking to convert the unbelievers in the river origin of the Old Red to staunch advocates of it. In fact, we may say that the case is so clear not only as to the lithogenesis of the deposits of the Old Red Sandstone, but also as to the medium in which the organisms of that time must have lived, that a few years' from now there will probably not be any thoughtful geologist who will not agree that the Devonic rivers supplied the sediments and were also the home of the Old Red fishes and merostomes. But in the case of the Wenlock it seems the rankest heresy to say that any of the organisms whose remains are found therein could be other than dwellers in the sea. The majority of palaeontologists would describe the Wenlock as exposed in the inliers north of the tableland in some such manner, "The Wenlock consists of a series of conglomerates, mudstones and grits with intercalated shale bands which are usually highly fossiliferous. While the coral fauna so characteristic of the Wenlock of England is lacking, there abounds, nevertheless, a representative marine assemblage which includes graptolites, brachiopods, pelecypods, gastropods, cephalopods, crustacea, and eurypterids. The merostome fauna is one of the largest known from a single horizon, comprising sixteen species, distributed in five genera, while the remains are so abundant that certain layers are almost like coal beds, they are so charged with carbon." Who, indeed, would have the temerity to claim that such a fauna of eurypterids with such asso-
