Yol. 59.] PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. ci 



diameter, such as those named Planolites by Nicholson ; another, of 

 the same material, had blunt ridges, tapering to a point, an inch or 

 so long, rudely parallel, in sets of about lour. These he should 

 have taken for the tracks of a (?) crustacean, but they were single, 

 not paired, and without any sign of a medial furrow. The third 

 was a slab, measuring about 1 L by 5 inches and 1 J inches thick, of a 

 brownish quartzite passing quickly on one side into a green argiJlite, 

 the other side being thickly studded with dome-like eminences about 

 an inch in diameter, and nearly half this in height. Most of them 

 show a slight ' dimple ' at the top, and a very slight ' step ' or 

 swelling often forms a sort of ring part way up the dome. Some 

 argillite, like that on the other side, remains about their bases, and 

 a few tracks of Planolites wind among them, and once or twice seem 

 to pass over them. The domes are formed of a quartzite, identical 

 with that of the slab. It shows a very faint stratification, and 

 consists of grains of quartz, not seldom well rounded, embedded in 

 a minutely-micaceous matrix, probably an alteration-product of 

 felspar. They cannot be concretions ; so the speaker regarded them 

 as the casts of pits in the argillite, made by a large annelid, which 

 retreated into it vertically (? Scolithui), afterwards filled up by a 

 layer of sand. 



The following communications were read : — 



1. ' The Age of the principal Lake-Basins between the Jura and 

 the Alps.' By Charles S. Du Riche Preller, M.A., Ph.D., A.M.I.C.E., 

 M.I.E.E., F.R.S.E., F.G.S. 



2. ' On a Shelly Boulder-Clay in the so-called Palagonite- 

 Formation of Iceland.' By Helgi Pjetursson, Cand. Sci. Nat. 

 (Communicated by Prof. W. W. Watts, M.A., M.Sc, Sec.G.S.) 



In addition to the specimens described above, the following 

 were exhibited : — 



Specimens of Alpine Rocks from the Zurich Gravel-Beds, 

 exhibited by Dr. C. S. Du Riche Preller, M.A., E.R.S.E., F.G.S., in 

 illustration of his paper. 



The following donations were also laid on the table : — 



A series of Fossil Brachiopoda illustrating the paper read on 

 February 4th, 1903, by G. W. Lamplugh, Esq., F.G.S., & J. F. 

 Walker, Esq., M.A., F.L.S., F.G.S., ' On a Fossiliferous Band at 

 the Top of the Lower Greensand at Shenley Hill, near Leighton 

 Buzzard (Bedfordshire),'" presented by the Authors. 



A sample of Yolcanic Ash which fell on Barbados between 11 a.m. 

 and 5 p.m. on Sunday, March 22nd, 1903, as the result of an 

 eruption of the St. Vincent Soufriere on that day. Collected at 

 Chelston, Bridgetown. Presented by Sir D. Morris, K.C.M.G., 

 Imperial Commissioner of Agriculture for the West Indies. 



Topographical Map of Switzerland, on the scale of 1 : 200,000, 

 presented by Dr. C. S. Du Riche Preller, M.A., F.R.S.E., F.G.S. 



