90 ' KJiFOKT — 1876. 



drawing illustrated the enlargement of the seventh pair of appendages iu this species 

 into swimming-feet. 



The species of Julus, called by the author J. conduns, shows how little the forms 

 of this genus have changed in the interval between Palasozoic and recent times. 



The rich materials which are now accumulated in the Museum of Prague will 

 require for their illustration about oO or 40 plates iu the mouogTaph which the 

 author is now preparing on this very interesting vertebrate fauna. 



On tlie Plvjsical Oeology and Geological Structure of Foula. 

 By Geokge a. Gibson, M.B., B.Sc. Edhth. 



Taking up, in the first place, the physiographical geology of the island, iu con- 

 nexion with the agencies involved, the paper describes the coast scenery, and dwells 

 "upon the contrast between the low and rugged eastern side and the stupendous 

 cliifs which overhang the western sea. This striking difference is shown to be due 

 partlj" to the superior powers of resistance to weathering evinced by the materials 

 of the sandstone rocks as contrasted with the crumbling schistose masses, aud also 

 to the fact that iu the former the strata dip away from the cliffs. 



The inland features are next taken up in detail. The five hills are found to bo 

 on the west side, three of them (Liorafield, the Sueug, and the Kauie, which, taken 

 by aneroid, reach 1000, 1250, and 1150 feet over sea-level) forming an axial chain, 

 w'hilst the other two (Soberly, CoO, and the Noup, 700 feet high) are distinct. 

 The last three are noticed as forming precipices from their summits sheer into the 

 sea, and all, except the Noup, whicli is dome-shaped, as having a conoid outline, 

 the steepest sides of which face the north and east. As the dip is S.S.W., these 

 hills are therefore held to have a contour in accordance with the empirical law, 

 noted above, that the strata dip away from the side wliich has the steepest slope. 

 The drainage is of course seen to be easterly. 



The lithological character of the rock masses is then detailed, along with their 

 architectural features and stratigraphical relations. The eastern side is described 

 as composed of gneiss, very similar to that of Loch Maree, aud of mica-schist with 

 intruded veins of granite, having a strike from N.W. to S.E., agreeing therefore 

 wiXh the presumably Laurentian of Scotland ; this, however, is not to be regarded as 

 of great significance, on account of the v.ariable strike of similar rocks in Shetland. 



The sandstone series is shown to be separated by a fault from the metamorphic 

 a-ocks, running from N.N.W. by N. to S.S.E. by S., and along which dislocation the 

 rocks are changed into hard quartz rock. There is described an unbroken succession 

 of sandstones and flags for two miles, at an average dip of more than 25°, whoso 

 thickness cannot bo estimated at less than 4400 feet. 



No fossils having been discovered in these rocks, they are then compared in litho- 

 logical character and position with the other sandstones of Slietland. DitFerences 

 in composition and texture are pointed out to be due to altered conditions of depo- 

 sition, the Bressay and I^Twick flags aud sandstones belonging, with the Foula 

 beds, to the Old iled Sandstone of the Caithness series. 



On the li^id Soil of Indict. By Dr. Gilchktst. 



On the Strata and Fossils hetween the Borrowdaile Series of the Goniston Flacjs 

 of the North of England. By Prof. Hahkness, F.R.'S., and Prof. A. H. 

 NicnoLSON, M.D. 



On the Upper Limit of tin essentially Manne Beds of the Cctrhoniferons 

 System of the British Isles, and the necessity for the esfahlishment of a 

 Middle Carboniferous Group). By Prof. Enw-iRD Hull, F.B.S., cjr., 

 Director of the Geological Survey of Ireland. 



In this paper the author endeavours to show the equivalent stagec throughoul 



