462 Lapworth & Wilson — Silurian Rocks of Roxburgh & Selkirk. 



of that line ; but this needs much fuller investigation. At one time, 

 we were of opinion that the Gala beds rested unconformably upon the 

 Moffat rocks, but we have been compelled to give vip this theory for 

 the southern area at least ; but there are many facts in the north 

 that appear to us utterly inexplicable, unless we admit a slight 

 unconformability or an overlap. 



Eetui-ning once more to the great anticlinal from which we started, 

 and proceeding thence up the strata as before, but this time in a 

 southerly direction, we find the Selkirk beds coming in their 

 proper place upon the Hawick Eocks, and containing Protovirgularia, 

 FJiyllopoda, and Annedides : but instead of the Moffat beds following 

 them, we have a thick series of rock of quite a different aspect, which 

 are called by us the Eiccarton beds, and are of Upper Silurian age. 

 We made the discovery in the spring of last year, and a paper by 

 one of us upon the subject was read before the Geological Section of - 

 the British Association at Liverpool. 



These rocks are found in five separate areas — 



1. In the well-known tract of country to the south of the town of 

 Kirkcudbright. 



2. To the south of the granite area of Criffel and Dumfries. 



3. In a long stretch of country extending from a point near 

 Lockerby to the Old Eed Sandstone near Stobbs Castle. 



4. In a large inlier surrounded by Old Eed Sandstone and Car- 

 boniferous, and reaching from the village of Oxnam, near Jedburgh, 

 to Ernton Fell on the Liddel. 



5. In a small patch at the head of the Kale Water, high up among 

 the porphyries and limestone of the Cheviot Hills. 



The northern boundary of these rocks seems to form an almost 

 exact straight line parallel with the average strike of the Lower 

 Silurian. It is very probably a fault, though we are xmable to prove 

 this. 



The strata in these districts are lithologically identical with those 

 of Kirkcudbright. They consist of grit and shale not unlike those 

 of the Lower Silurian, but there are hundreds of little bands of car- 

 bonaceous schist full of Graptolites, always, however, in a very bad 

 state of preservation. The whole set of beds are very calcareous, 

 more especially the dark shales. 



The fossils are — Bhynclionella niicula, Orthoceras tenuicinctum, 0. ibex, 

 0. tracheale, Graptolithus priodon, G. colonus, and Flemingii, together 

 with many forms of Phyllopoda, etc., such as Ceratiocaris and 

 Aptycliopsis, and possibly Pterygotus. We have also found specimens 

 of Cyrtograpsus, Ptilograpsus, and Inocaidis, genera new to Scotland. 



Thus, in the country examined by us, there appears to be five 

 distinct and separate groups of Silurian strata, the first two differing 

 in lithological characters alone, none of the fossil forms found in 

 them being of any value in estimating their age. 



The superior groups, however, contain a great number of fossils, 

 and their place in the Silurian system can be apj)roximately ascer- 

 tained. The number of species known to us has not been made up 

 without a very large amount of labour and research. When it is re- 



