Page:The Geologist, volume 5.djvu/167

Rh taceans, possibly some of the same animals as those that left the Protichnital trail-markings on the surfaces of the sandstone.

The Climactichnites is also analogous, in respect to its transverse bars, to the Crassopodia Embletonii, Tate ('Geologist,' vol. ii. p. 66, pl. 2, fig. 2; and 'Berwickshire Nat. Field-club Transact.,' vol. iv. p. 104, pl. 1, fig. 2), which, according to Mr. A. Hancock's views (loc. cit., p. 456), would be an infallen gallery, probably made by a Trilobite belonging either to the genus Phillipsia or Griffithides.

Trilobites, and those of large size, are present in some of the older palæozoic rocks of North America, not far from the geological horizon of the Potsdam Sandstone ; and, although they do not appear to have been preserved in this littoral sandstone, yet there is the possibility of their having frequented the shallow waters of that old sea, just as the Trilobites of the Carboniferous period probably furrowed the Lower Carboniferous sands without being preserved therein. If, however, Limuloid animals made the trails above mentioned, we must remember that, according to Mr. W. H. Baily, the so-called "Limuli" of the Coal-period, or more properly the Bellinuri, are more closely allied to the Trilobite than to the Limulus, having well-defined thoracic segments; and therefore probably true Limuli had nothing to do with the production of any of the Protichnital trails. Trilobital, Bellinural, Amphipodal and other Crustaceans, with sea-worms and molluscs, may have made most of the trails, runs, or tracks that we have to do with in the Palæozoic rocks, and even insects may have aided in some instances, as intimated by Mr. Emmons,—but we want much more information in nearly all cases. Nor are we better off as regards our knowledge of similar markings in the Secondary and Tertiary strata. It is hoped that the foregoing notes may suggest further research in the right direction.

The mountainous district known as the Eifel, or Eifel-Gebirge, in Rhenish-Prussia, is, as all geologists know, famous for the numerous well-preserved craters of extinct volcanos and for the lava-streams, scoriæ, trachyte, and basalt connected therewith.

The English reader will find a short account of the tertiary and volcanic rocks of the Eifel in Lyell's 'Manual of Geology,' chapter xxxi.; and a good geological map of the Eifel and neighbouring districts is appended to a paper, by Sedgwick and Murchison, on the Rhenish Provinces, in the Transactions of the Geological Society, 2nd series, vol. vi. part 2. In the Eifel there are two extensive areas, in which volcanic activity has been especially intense. One of