104 



REPORT 1871. 



The Hawick and Selkirk rocks fill up all the central portion of the district de- 

 scribed, extending from near Selkirk to Mosspaul. They form the great anticline 

 of the South Scottish Silurians, and appear to be the lowest rocks exhibited. Thoy 

 contain a few fossils, such as Annelida, Protichnitcs, Protovirgularia, PJii/llopoda. 



The Moffiit series is remarkable for the bed (or beds) of anthracitic shale which it 

 contains, and which is famous for the large number of Graptohtes foimd in it. The 

 Moffat series, with its black shale-band, makes its appearance twice in the district 

 described, — 1st, in the country between Selkirk and Melrose ; 2nd, in the region of 

 the Moorfoot Hills ; these beds yield fossils of the genera Dicellof/rapsus, Uicrano- 

 [/rapsus, Cladof/rapsus, Climacoyrcqjsus, Discinocaris, Peltocaris, Siplwnotreta, Lin- 

 (jula. 



The Gala gi-oup lies in the syncline formed by these two appearances of the 

 IMoftiit series, and consists of grits, sandstones, shales, and conglomerates, that im- 

 bed a Middle Silurian fauna, including Monoyrapsus, Diploi/rapsus, RctioUtcs, Die- 

 tyunema, Apti/cfiojysis, Ceratiocans, Didyocaris, Orthoceras. 



The Eiccarton beds fill up all the Silurian country to the south of a line drawn 

 from Ku'kcudbright to Jedbm-gh. The fossils are Upper Silurian, and include Cyr- 

 toyrapsus, Ptiloyrapstis, Thecn, Ortlioceras, Ceraiiocaris, Aptycliopsis, Ptcryyotus, 

 Phynchonella. 



The authors believe that the anthracitic bed of Moffat is of Bala age, that the 

 Gala gi-oup contains strata of both Caradoc and Llandovery age, and that the 

 Eiccarton beds should be classed with the Wenlock or Lower Ludlow. 



On the GraptoUtes of the Gala Group. By Charles Lapworth. 



The Graptolites found in the Gala group form an assemblage quite distinct from 

 that aflbrded by the Moffat series. The species known at present are : — 



Two of these species, i. e. RdioUtes obesus and Graptolites socialis, are new to 

 science. 



In Rctiolites ohcsm the frond is diprionidian, ensiform, or elongate-elliptical in 

 form, with a length of 1^ inch in the largest specimens, to a breadth of more 

 than ^ of an inch. The meshes on the central surface are hexagonal, J^of an inch 

 in diameter. Eound the inner margin of the frond runs a series of large subqua- 

 draugular meshes, which forms a peculiar and characteristic braiding, distinguish- 

 ing this form at once from all other species of the same genus. These meshes 

 show the place of the cellules, which are from 22 to 24 to the inch. 



Graptolites socialis is monoprionidian, flagelliform, -g\ of an inch in width and 

 less than 2 inches in length. The cellules are formed after the type of those of 

 Graptolites Beckii (Barr.). They are arranged along the concave side of the stipe, 

 from .34 to 44 to the inch. 



This species is found in great numbers in some of the Gala beds. 



On the Origin of Volcanoes. By P. "W. Stuart Menteath. 



The author's views are briefly stated in ' Scientific Opinion ' for April 7, 18G9. 

 Since that date, M. Fouqut5 in France, and Peschel in Germany, had published 

 very similar views, although M. Fouque, until lately, opposed all chemical theories 

 of the origin of volcanoes. The author, therefore, ventured to bring forward his 

 theory more in detail, and he believed that if chemical geology were more gene- 



