Fig. 9.—Astropolithon Hindii, an organism of the Lower Cambrian of Nova Scotia, possibly vegetable.
It is worthy of note that these markings strikingly resemble the so-called Eophyton, described by Torell from the Primordial of Sweden, and by Billings from that of Newfoundland; and which also occur abundantly in the Primordial of New Brunswick. After examining a series of these markings from Sweden shown to me by Mr. Carruthers in London, and also specimens from Newfoundland and a large number in situ at St. John, I am convinced that they cannot be plants, but must be markings of the nature of Rhabdichnites. This conclusion is based on the absence of carbonaceous matter, the intimate union of the markings with the surface of the stone, their indefinite forms, their want of nodes or appendages, and their markings being always of such a nature as could be produced by scratches of a sharp instrument. Since, however, fishes are yet unknown in beds of this age, they may possibly be referred to the feet or spinous tails of swimming crustaceans. Salter has already suggested this origin for some scratches of somewhat different form found in the Primordial of Great Britain. He supposed them to have been the work of species of Hymenocaris. These marks may, however, indicate the existence of some free-swimming animals of the Primordial seas as yet unknown to us.
Three other suggestions merit consideration in this connection. One is that Algæ and also land-plants, drifting with tides or currents, often make the most remarkable and fantastic trails. A marking of this kind has been observed by Dr. G. M. Dawson to be produced by a drifted Laminaria, and in complexity it resembled the extraordinary Ænigmichnus multiformis of Hitchcock from the Connecticut sandstones. Much more simple markings of this kind would suffice to give species of Eophyton. Another is furnished by a fact stated to the author by Prof. Morse, namely, that Lingulæ, when dislodged from their burrows, trail themselves over the bottom like worms, by means of their cirri. Colonies of these creatures, so abundant in the Primordial, may, when obliged to remove, have covered the surfaces of beds of mud with vermicular markings. The third is that the Rhabdichnite-markings resemble some of the grooves in Silurian rocks which have been referred to trails of Gasteropods, as, for instance, those from the Clinton group, described by Hall.
Another kind of markings not even organic, but altogether depending on physical causes, are the beautiful branching rill-marks produced by the oozing of water out of mud and sand-banks left by the tide, and which sometimes cover great surfaces with the most elaborate tracery, on the modern tidal shores as well as in some of the most ancient rocks. Dendrophycus[V] of Lesquereux seems to be an example of rill-mark, as well as Aristophycus, Clœphycus, and Zygopliycus, of Miller and Dyer, from the Lower Silurian.
[V] “Coal Flora of Pennsylvania,” vol. iii., Plate 88.
Rill-marks occur in very old rocks,[W] but are perhaps most beautifully preserved in the Carboniferous shales and argillaceous sandstones, and even more elaborately on the modern mud-banks of the Bay of Fundy.[X] Some of these simulate ferns and fronds of Laminariæ, and others resemble roots, fucoids allied to Buthotrephis, or the radiating worm-burrows already referred to ([Fig. 10]).
[W] “Journal of the Geological Society,” vol. xii., p. 251.
[X] “Acadian Geology,” 2d ed., p. 26.
