614 TRANSACTIONS OF SECTION C. 



similar to the ' stigmata ' found in scorpions and other arachnids, suggesting that 

 it may be a fragment of an air-breathing animal. 



Specimen 4, from Shipley, is probably one of the first abdominal segments of 

 Ec corpius sp., two specimens of which genus have been found in this district — 

 on:, described by Professor Huxley, 1 from near Chesterfield, and another, at 

 present undescribed, found by the author in the Digby Claypit, Kimberley, 

 Nottinghamshire. 



Specimen 5, from Brindsley, Nottinghamshire, is a single segment of an 

 arthropod, and possibly belongs to an Eurypterus. 



Specimen 6, from Shipley, is the wing of an insect probably belonging to the 

 order Palseodictyoptera of Scudder. 



Specimens 7 and 8, also from Shipley, are a fragment of a much smaller 

 insect's wing, which, in its incomplete state, would be impossible to assign,to any 

 definite order. 



Insects' wings are very uncommon in the Coal Measures of this district, only 

 one having been found near Chesterfield, and described by S. H. Scudder 2 under 

 the name of ArchosoptUus ingens, 



8. The Origin of the British Trias. By A. R. Hokwood. 



As a result of an investigation covering the Midland area, and especially 

 from a study of the Upper Keuper of Leicestershire, the author, who has been 

 aided in this research by a grant from the Government Grant Committee of the 

 Royal Society, has arrived at the conclusion that, in so far as Great Britain is 

 concerned, the Trias was laid down under delta conditions, during which, as in 

 the Nile area to-day, seolian action took place, but was not responsible for 

 deposition except locally on a small scale, and following the prevalent wind course. 



The premisses upon which this view is based are as follows : — • 



1. There is a continuity of area of deposition during the Upper Carboniferous, 

 Permian, and Triassic periods, and a relative homology between the different 

 parts of each — i.e., the base of each is similarly coarser than the top, and each 

 has a red phase ultimately. 



2. There is a gradual gradation from coarse sediments to finer from below 

 upwards, as in modern (and other fossil) deltas. For instance, pebbles pre- 

 dominate in the lower phase, coarse sandstones (with occasional pebbles) in 

 the centre, and finer and finer marls succeed in the last phase, which becomes 

 increasingly ferruginous, as it merges into the lake-phase of the delta period. 



3. The oldest member of the series, the Bunter, is acknowledged to be a 

 delta- formation — as Professor Bonney showed many years ago — and there is no 

 evidence for the discontinuity of the agency producing that mode of deposition. 



4. The continuity of the Bunter and Keuper is an argument for the extension 

 of delta conditions to the Keuper, some ' basement beds ' being indistinguishable 

 from the Bunter. 



5. The general evidence of an oscillation of level in early Triassic times and of 

 overlapping is a proof of aqueous agency. Coupled together these vertical and 

 horizontal movements are more distinctive of fiuviatile than lacustrine or marine 

 conditions. 



6. There is a close analogy between the contour or geographical configura- 

 tion of the Trias (whether we consider concealed or exposed areas), and modern 

 deltas — e.g., the Mississippi, with its dactyloid extensions beyond the head. 



7. There is a distinct analogy between the regular alternations of, pebbles or 

 sand and marl and seasons of torrential rains and floods or drought ; that is to 

 say, one sort of sediment is brought down at one period of the year, another 

 at another. This may be witnessed in modern accumulations such as those of 

 the Nile or Mississippi, where floods occur. These alternations are due to over- 

 flow of banks where ' skerries ' lie on the hilly grounds now, just as they did 

 when they were deposited. The grey marl is heavier than the red. and deposits 

 are arranged as in a diffusion column. 



1 Reference not determinable. 



* S. H. Scudder, ' Haxapod Insects of Great Britain,' Mem. Boston Nat. Hist. 

 Soc, vol. iii., pp. 217-218, 1873-1894. 



