J. Reid Moil — Sub-crag Flints. 553 



when the marine period of the Lower Carboniferous was drawing to 

 a close and a general elevation was taking place. Similar conclusions 

 could be drawn from the Gotlandian and other periods recorded above. 



In conclusion I venture to express the hope that however incomplete 

 the account of the succession of forms which I have given may be, it 

 may nevertheless help to stimulate an interest in these rock-building 

 Algae and encourage geological workers in this country to turn their 

 attention to a hitherto neglected group of forms of great strati- 

 graphical importance. 



In the accompanying Table II are set out the more important Algal 

 horizons so far described in the Palaeozoic and Mesozoic rocks, 

 together with a few typical occurrences of Tertiary age, but the 

 table makes no claim to be exhaustive, as additional evidence of the 

 importance of these organisms is constantly coming to hand ; thus 

 since the publication of the last number of this Magazine I have 

 received from Professor Rothpletz ^ a description of a new form of 

 Spherocodium, S. zimmermanni, which he finds playing an important 

 part in the ' so-called conglomerate ' in calcareous sandstone near 

 Liebichan Silesia, formerly classed as Culm, but which has recently 

 been shown by Zimmermann to be of Upper Devonian age. 



Y. — The Sdb-cb,ag Flints. 

 By J. Keid Moie, F.G.S. 



T the meeting of the Britisli Association held at Birmingham 

 last September, Professor VV. J. Sollas, F.R.S., read a paper in 

 which the Sub-crag flints I have discovered were rejected as not being 

 of human workmansliip. Professor Sollas mainly based his arguments 

 upon certain flints found upon the seashore at Selsey Bill, Sussex, 

 many of which have been collected by Mr. E. Heron Allen of that 

 place. In August of this year I paid a visit to Selsey and, owing to 

 the kindness of Mr. Heron Allen, was enabled to carefully examine 

 his collection of flints and the exact places on the shore from which 

 they were derived. 



The conclusions I arrived at regarding these specimens and their 

 method of fracture are as follows : — 



An examination of the flints in Mr. Heron Allen's collection from 

 the surface of the Eocene clay at Selsey Bill clearly shows that they 

 differ widely both in mineral condition and ' patination ', and do not 

 belong to one geological period. When each series is arranged apart 

 the specimens are seen to resemble very closely those found in East 

 Anglia (1) below the Red Crag, (2) in the Middle Glacial Gravel, 

 and (3) in the Chalky Boulder-clay. 



The occurrence of flints of these three series at one horizon in the 

 South of England is of some interest and importance, and seems to 

 indicate the breaking up of these deposits and subsequent deposition of 

 their material at the spot where they are now found. The specimens 



^ ' ' Uber Sphcerocodmm Zitnmerinanni aus dem Oberdevon Schlesiens ' ' : 

 Jahrb. d. k. Preuss. Geol. Landesanstalt, 1911, Bd. xxxii, T. ii, Hft. i, p. 112, 

 pis. 4, 5. 



