HARDWICKE'S SCIENCE-GOSSIP. 



247 



too the spathulate-leaved sundew (Drosera intermedia), 

 45. To-day (June 1, 1879) there were shown me, what 

 I've seen before and since, small-flowered specimens 

 of one of the common buttercups (Kan. acris) ; the 

 blooms were scarcely ^ inch across. 



June 2. From Shoreham, near Brighton, I received 

 parsnip (Pastinaca saliva), 52 ; a plant not in flower, 

 but which I believe to be Artemisia mar it i ma, 46 

 (the sea wormwood) ; the red spur-valerian (in bud) 

 \Centranthus ruder] ; and beet (Beta maritime), 37. 



June 3. H. Ibbotson handed me from Hawnby, near 

 Ilelmsley, east of Thirsk: — Baneberry or herb Christo- 

 pher (Acteea spicata), 5 ; Teesdalia nudicaitlis, 61, 

 named after the Robert Teesdale of Castle Howard 

 whose " Plantse Eboracenses " &c, are referred to in 

 the Science-Gossip of last January (page 3) ; the 

 red-fruited stone bramble (Rubus saxatilis), 50; Herb 

 Paris (Paris quadrifolia), 70 (this occurs in three 

 localities near York ; — Copmanthorpe, Skelton, and 

 Langwith woods) ; the fingered sedge (Carex digi- 

 tata), 12 ; the mountain melic-grass (M. nutans), 36 

 [in 1877 this was mentioned to me as found together 

 with the deadly nightshade (Atropa Belladonna), 28, 

 and fly orchis {Ophrys museifera), 42, at Sherburn, 

 near the battlefield of Towton]. 



York, March, 1880. B. B. Le Tall, b.a. 



P.S. — I hear that the resolution to use Strensall 

 Common for military purposes is abandoned. Also, 

 since writing the above, the " Rose of Jericho" has 

 been sufficiently well discussed in these pages. 



NOTES ON THE PRE-CAMBRIAN SYSTEM 

 OF AMERICA. 



By C. H. Octavius Curtis, Ex-Science Exhib., 

 St. John's Coll., Cambridge. 



BELOW the Cambrian System, there occurs in 

 many parts of the world an immense series of 

 rocks many thousands of feet in thickness, and of a 

 crystalline nature, composed of gneiss, mica, schists, 

 ophiolites, and limestones. 



Such was the nature of a formation that Sir W. 

 Logan discovered in the vicinity of the St. Lawrence, 

 where they covered an area of some 200,000 square 

 miles. His studies in this series brought him to the 

 conclusion that they had a perfect right to a place in 

 the historical scale of rocks, and were not, as had 

 formerly been considered, altered granites, the result 

 of the cooling of our planet, but were nothing more 

 nor less than a metamorphosed series of rocks which 

 had passed through stages similar to those which 

 other formations are now undergoing; and his conclu- 

 sion was strengthened by the discovery of what was 

 considered to be an organic structure (Eozoon Cana- 

 dense) of low type largely prevalent in this mass. 



He therefore looked upon these rocks as the 

 earliest series that the historical geologist has to 



deal with, and classed all together in a system to 

 which he gave the name Laurentian. 



After Logan's opinions became known, geologists 

 in the New World set to work to see if it were 

 possible to find any traces of a system that could be 

 considered homotaxial with the American Laurentian. 

 It now became evident that in our own country there 

 were beds of a nature related to those of the St. 

 Lawrence valley, and that they were overlaid uncon- 

 formably by the Older Cambrian. Such were found 

 to occur in Wales, Anglesea, the Malvern, and 

 Charnwood, while Sir R. Murchison's "Fundamental 

 gneiss " of North Ross-shire, Sutherlandshire, 

 Lewis, and The Hebrides, all agreed with the Lauren- 

 tian type. 



Gumbel and Hochstetter pointed out a similar 

 series in Bohemia and Bavaria, and were fortunate 

 enough to find an Eozoon only differing from Logan's 

 species in a very small degree. 



The Scandinavian geologists had no difficulty in 

 correlating their " Striped Granite " with Laurentian 

 beds. 



Logan by no means rested content with his 

 discovery, but was very soon brought to the conclu- 

 sion that he had a twofold series to deal with, 

 separated by a great unconformability. 



The Lower Laurentian, or Laurentian, consisted 

 of orthoclase gneiss, sometimes granitoid, with quartz- 

 ites, passing into conglomerates (in part) hornblendic 

 and micaceous schists, augite rock, serpentine and 

 limestones, the latter being sometimes dolomitic and 

 largely crystalline. 



The thickness of this series was found to be 20,000, 

 while its Bohemian representative amounted to 90,000, 

 feet. It was in this series that the organism known as 

 Eozoon Canadense was found.* The nature of this 

 supposed fossil is too well known for me to delay 

 the reader by describing it. It may be well to mention 

 that while it is looked upon as a fossil by many of 

 the ablest authorities, among whom I may mention 

 Bradley, Carpenter, Dawson, Gumbel, Jones, and 

 Parker, all of whom take it for a gigantic foraminifer 

 having affinities to the Rotaline genera Polytrema 

 and Calcarina ; on the other hand, many petrogra- 

 phers are inclined to treat it as a mineral structure, 

 having no relation to the organic kingdom. Professor 

 Mobius, a once strenuous upholder of the fossil 

 doctrine, has recently, as the result of many years' 

 work, published a monograph in which he strongly 

 upholds its mineral nature. f The discussion, how- 

 ever, is of little moment, as there is ample evidence 

 of the occurrence of life in these beds, in the presence 

 of limestone and graphite. 



The Upper Laurentian or Labrador Series. — As has 

 formerly been said, this series rests unconformably on 



* See Nicholson's "Palaeontology," vol. i. Q.T.G.S., xxi. 

 45-5° (Logan), xxi. 51-5'j (Dawson), xxi. 59-66, and xx. 219-22S 

 (Carpenter), xxii. 185-216, (King and Rowney). 



t See " Nature," vol. for 1879, Mobius. 



