It appears that Dr. Sterry Hunt and Dr. Dawson have recently had their attention particularly directed to the specimens from Arisaig deposited in the Museum of the Geological Survey at Montreal, and they have discovered in them well-defined Eozoonal structure, which they consider as conclusive evidence of the Laurentian age of the rocks in question (see Prof. Hind's letter to Mr. Robert Roberts). I have already stated that the band is bounded on the east side by carboniferous rocks. It is still quite possible that intermediate formations may appear on the south side of the band. Where the country is exposed, to the south of the band we find a considerable breadth of Carboniferous formation, consisting of conglomerates and grits largely composed of debris of the Laurentian rocks described, with limestone and coal-measures (vide Dawson's 'Acadian Geology,' 2nd edition). These are arranged in trough-shape. The conglomerates of the south side of the trough rest on the north side of an anticlinal series of metamorphic Upper Silurian, while on the south side of this anticlinal there rest con- glomerates with a great band of limestones and gypsum, with a basin of gypsum clays. At Antigonish these clays are saliferous to the depth of at least 610 feet.
Note on some Entomostraca from Akisaig. By Prof. T. R. Jones.
The specimens are bivalved Entomostraca (four species) of Upper- Silurian types in three pieces of reddish fossiliferous limestone from Arisaig, with Strophomena, Stenopora, Trilobites, &c.
No. 1. Two very fine specimens of the valves, right and left, of Beyrichia tuberculata, Kloeden, sp, (Annals Nat. Hist. ser. 2, vol. xvi. p. 86). This may be the same form as that described by Prof. James Hall as Beyrichia pustalosa, ' Canadian Nat. and Geol.' vol. v. p. 158, fig. 19 (woodcut).
No. 2. Several specimens of Beyrichia Wilkensiana, Jones (Ann. Nat. Hist. ser. 2, vol. xvi. p. 89).
No. 3. Two valves of Beyrichia Maccoyiana. Jones (Ann. Nat. Hist. ser. 2, vol. xvi. p. 88), or a very closely allied species. Also a very small Primitia, referred to in Ann. Nat. Hist. ser. 3, vol. xvi. p. 424, as being probably the same as P. concinna, Jones.
This may be the form described by Prof. James Hall as Leperditia sinuata (Canadian Nat. and Geol. vol. v. p. 158 ; no figure given). This little Primitia is more oblong than the figured P. concinna, and narrower than P. mundula, which it otherwise much resembles : a similar form occurs in the Upper Silurian Limestone at Dudley and in Gothland.
Discussion.
Sir W. Logan said that Dr. Hunt had seen the specimens of serpentinous limestone, and considered that they might be Laurentian. Sections of them appeared to Dr. Dawson to show tubulation rather different from that found in Laurentian Eozoon. They might, therefore, belong to a different age.
