In Southern New Brunswick, Matthew indicated, several years ago, the occurrence of certain conglomerates and sandy and slaty beds over the rocks, mostly of igneous origin, constituting a great thickness of beds under the Cambrian, and known locally as the "Coldbrook" series, which is probably equivalent to the Huronian of Northern and Western Canada, to be noticed later. These beds were at first regarded as an upper member of the Huronian, but subsequently it was thought better to unite them with the overlying Cambrian as basal Cambrian. The fact that these problematical beds were ascertained to be unconformable to the Cambrian, and the peculiarity of their fossils, led to their being constituted a separate group under the name Etcheminian, which seems to represent a time and conditions introductory to the Cambrian ([Fig. 10]). The fossils in these beds are few and hard to find. Matthew has kindly furnished me with the following list.[7] The Trilobites are conspicuous by their absence. Sea-worms have left burrows, trails, and casts, which probably represent several species ([Fig. 11]). A single little shell (Volborthella) is supposed to be a precursor of the straight chambered shells allied to the modern nautilus, which become so large and numerous in succeeding periods. There are a few univalve shell-fishes allied to modern sea-snails, a brachiopod of the antique genus Obolus, some fragments supposed to represent Cystideans, a rudimentary type of the stalked sea-stars so abundant later, spicules of sponges and minute Protozoa, with shells not unlike those of their modern successors. This meagre list sums up the forms of life known in the Etcheminian of this district, one in which the Cambrian beds exhibit the rich and varied fauna of Trilobites and other animals described and figured by Matthew in several successive volumes of the "Transactions of the Royal Society of Canada" ([Fig. 12]).
[7] "Transactions Royal Society of Canada," vol. vii.
Fig. 11.—Trails of Worms of two types (Psammchnites and Planilites).
Beds in Newfoundland (the Signal Hill and Random Sound series), underlying the Lower Cambrian, have afforded to Murray and Billings some well-characterized worm-castings of spiral form, and a few problematical forms known as Aspidella, which may be Crustaceans or Mollusks allied to the limpets ([Fig. 13]).
Fig. 12.—Group of pre-Cambrian (Etcheminian) Animals from the Etcheminian. (After Matthew.)
The name "Etcheminian" is derived from that of an ancient Indian tribe of New Brunswick.
(a) Volborthella, supposed to be a Cephalopod shell. (b) Pelagiella. (c) Orthotheca, supposed to be Pteropods. (d) Primitia, an Ostracod Crustacean, (e) Obolus, a Brachiopod shell. (f) Platysolenites, probably fragment of a Cystidean. (g) Globigerinæ, casts of Foraminiferal shells, Etcheminian, New Brunswick.
Fig. 13.—Arenicolites (Spiroscolex) spirales (Billings) and Aspidella tenanovica (Billings), Signal Hill Series, Newfoundland.
