702 MR. J. E. MARE AND DR. H. A. NICHOLSOIf 



confeHus-heds is greater here than in any other section except 

 where we have indications of repetition. 



The shales above the co7ifertus-'beds are also Graptolitic and are 

 very similar to the con/^r^t^s-shales in lithological characters, being 

 fissile and having a ferruginous staining due to weathering. The 

 fossils are different : — 



Monograptus fimbriatus, Nich. 



gregarius, Lapw. 



attenuatus, Hopk. 



triangulatus, HarJcn. 



Hastrites peregrinus, Barr. 

 Diplograptus sinuatus, Nich. 

 Climacograptus normalis, Lapw. 



There is no doubt that these are the shales of the fim'briatus-zoin.% 

 and another argument of the succession being here complete is far- 

 nisbed by the fact that Monograptus triangulatus is here very abun- 

 dant, while elsewhere it is rare. It will be eventually seen that 

 this form marks the lowest horizon of the representatives of the 

 Middle Skelgill Beds in other areas. 



The beds of the Middle Skelgill group above the fimhriatus-^h.dXes 

 are extremely disturbed in this section. They are best exposed on 

 the left bank of the stream. A crush occurs between the Jimhriatus- 

 shales and the succeeding beds, which are blue mudstones, probably 

 forming the top of the zone of PJiacops glaber, as the succeeding 

 shales appear to belong to the convolutus-zone. In this case the 

 zones of Encrinurus jpunctatus and Monogra'ptus argenteus are 

 entirely faulted out. As our time for examining this section was 

 limited, and the Middle Skelgill Beds seemed to be of normal character, 

 we did not work them out in detail, a task of some difficulty owing 

 to their extremely folded condition. The beds which we refer to 

 the convolutus-zone have the ordinary appearance of the shales of 

 that horizon, and exhibit the very marked olive-brown staining 

 which distinguishes its deposits. Above them are some blue mud- 

 stones ; but a considerable fault occurs between the Middle Skelgill 

 Beds and the lowest exposed beds of the Upper Skelgill group. 

 The section of the representatives of this group is one of considerable 

 importance, and we worked it carefully. 



Ac 3. Eeturning to the right bank, an angle of the bank is seen 

 jutting out into the stream at some little distance below a waterfall. 

 In this angle some very black shales, interbedded with lighter bands, 

 appear for about 2 feet below the overlying mudstones. The upper- 

 most black shales have well-preserved Graptolites, including : — 



Monograptus spinigerus, Nich, 



distans, Portl. 



leptotheca, Lapw. 



lobiferus, M'Coy. 



Eastrites urceolus, Eichter. 

 Diplograptus Hughesii, Nick. 

 Ohmacograptus normahs, Lapw. 



Monograptus spinigerus occurs in the usual numbers, and indicates 

 that this is undoubtedly the zone characterized by that species. 



The succeeding beds of the Upper Skelgill group offer interesting 

 differences from those of other sections. 



Ac 4. No less than 30 feet of blue mudstones overlie the shales of 



