492: PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 11, 
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 Mon- 
treal, and they have discovered in them well-defined Kozoonal 
structure, which they consider as conclusive evidence of the Lau- 
rentian age of the rocks in question (see Prof. Hind’s letter to Mr. 
Robert Roberts). Ihave 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 hand. 
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 débris of the Lau- 
rentian 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 Entomosrraca from Artsaic. By Prof. T. R. Jonuzs. 
The specimens are bivalyed Entomostraca (four species) of Upper- 
Silurian types in three pieces of reddish fossiliferous limestone from 
Arisaig, with Strophomena, Stenopora, Trilobites, &e. 
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 pustulosa, ‘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 Matcoyiana, 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 
simuata (Canadian Nat. and Geol. vol. v. p. 158; no figure given). 
This little Primitea is more oblong than the figured P. concinne, 
and narrower than P., mundula, which it otherwise much resem- 
bles: a similar form occurs in the Upper Silurian Limestone at 
Dudley and in Gothland. 
Discussron. 
Sir W. Locan said that Dr. Hunt had seen the specimens of ser- 
pentinous 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 Hozoon. ‘They might, 
therefore, belong to a different age. 
