242 Proceedings of the Royal Physical Society. 
barriers that held in the Ballagan lagoons. South of the Firth of Forth, a 
similar series of deposits is exposed towards the base of the group on the 
shore near Cockburnspath. 
Still farther to the south, the Merse of Berwickshire is floored by a group 
of rocks of Ballagan type.' Towards the base they are much more estuarine 
in character, for they hold a crustacean and fish fauna not unlike that of the 
Langholm Scorpion bed, though many of the species are different. In both 
areas the specimens are preserved whole and in large numbers, as if they had 
been poisoned by volcanic exhalations, That they were laid down in close 
proximity to land is shown by their having yielded at least two genera of 
myriopods, in addition to scorpions as well as the perfectly preserved plant 
stems described by Dr Kidston. The lagoons here appear to have been 
banked up on the south partly by the Old Cheviot land surface. To the 
east they may have been blocked up by sandbanks, for the Fell Sandstones 
cross over into Scotland near Berwick-on-Tweed. 
Farther to the south-west, in Liddisdale, a modification of the Ballagan 
type recurs with the estuarine and even open-sea type of sedimentation ; 
each bed being accompanied by characteristic faunas. The Birrenswark 
Voleanic Zone, at the top of the Upper Old Red succession, is overlaid by 
the Whita Sandstones denoting shallow moving water. These are followed by 
a set of clays which alternate with limestones made up almost entirely of the 
brachiopod Seminula (Camarophoria) crumena, indicating comparatively clear 
water marine conditions. These beds are in turn succeeded by alternations 
of sandstones, clays and bands of lamellibranch limestone in which Modiolas 
like JZ. macadami or Schizodus are the only fossils, but some of the larger 
bands contain several species of lamellibranchs. Spzvorbis limestones are 
also of constant recurrence among these sediments. Some of the calcareous 
sandstones are full of small Murchisonid gasteropods. Towards the top 
there are occurrences of limestone of a more marine character, and one of the 
calcareous clays contains numbers of the brachiopod Syringothyris cuspidata, 
which genus Vaughan uses as the characteristic form of his Syringothyris 
zone. Near the top of the group comes the Thorlieshope Limestone with a 
truly clear water marine fauna in which junciform Lithostrotion, several 
brachiopods, and other organisms are found. 
Another limestone nearer the top of the group is entirely made up of the 
curious organism named by Nicholson Micheldinia, the exact nature of which 
is still problematical. One thing is certain, that it must have grown in 
water almost free from sediment. Estuarine conditions are shown towards 
the very top in the Tarras Water bed, yielding fishes and higher crustaceans. 
! Tuedian Beds of Howse, 
