526 Reports & Proceedings — British Association. 



group of sediments, but it has proved to be the oldest sedimentary 

 series. The Keewatin rocks, essentially schists and greenstones, 

 represent, for the most part, submarine lava-flows. On the surface 

 of these flows were deposited the Grenville sediments. While the 

 major part of the Grenville is later than the major part of the 

 Keewatin, a minor part of one group is contemporaneous with 

 a minor part of the other. It is remarkable that among the oldest 

 series of Australia, India, Africa, and other countries are rocks that 

 resemble very closely the Keewatin of Canada, with its associated 

 iron formation or jaspilyte. 



Among most of the workers on the pre-Cambrian of North 

 America there is now general agreement as to the age relations of 

 the rocks, but different classifications and nomenclatures are 

 employed. Most authors make a dual subdivision of the pre- 

 Cambrian which seems to the author to be purely arbitrary and 

 based on a, misconception. There is no proof that the unconformity 

 at the base of the Timiskamian is of less magnitude than that at the 

 base of the Animikean, or vice versa. 



5. The Plant-bearing Cherts at Rhynie, Aberdeenshire. — Report 

 of the Committee, consisting of Dr. J. Horne (Chairman), Dr. W. 

 Mackie (Secretary), and Drs. J. S. Flett, W. T. Gordon, 

 G. Sickling, R. Kidston, B. K Peach, and D. M. S. Watson, 

 appointed to excavate Critical Sections therein. 

 The plant-bearing cherts discovered by Dr. Mackie in the Old 

 Red Sandstone at Rhynie, Aberdeenshire, when examined under the 

 microscope, showed fragments of Crustacea in certain sections. 

 Some of the sections were submitted to Dr. W. T. Caiman and 

 Mr. D. I. Scourfield, who have furnished the following report: 

 " The animal remains are, for the most part, very fragmentary and 

 confused, but they are in an excellent state of preservation, even the 

 fine feathering on small setae being, in some cases, easily recognizable 

 All the remains examined appear to be referable to the class 

 Crustacea, and to have belonged to animals comparable in size to the 

 Copepoda of the present day. The most complete portions hitherto 

 found have been tails, consisting each of a number of segments and 

 ending in a furca. Both lateral and dorsal views have been seen, 

 and the general arrangement of the parts fairly well made out. Two- 

 distinct species appear to be represented, belonging either to a 

 primitive group of the Copepoda or to the very small Branchiopoda 

 (? Anostraca). Fragments of appendages are numerous in nearly all 

 the slides, but are extremely difficult to interpret. One slide, 

 however, shows a series of about three pairs of biramous feet in their 

 natural connexions. They are remarkably similar to the swimming- 

 feet of Copepods of the genus Cyclops, except that the branches are 

 unjointed instead of being composed of the usual three segments. 

 A considerable number of detached mandibles have also been seen, 

 all of them most closely comparable to those of the Branchiopoda. 

 It is evident that these remains are of extraordinary interest, and, 

 although little progress has been made towards reconstructing any 



