230 MISS G. R. WATNEI AXD MISS E. G. WELCH ON THE [May I9H r 



oclireous colour. The heads of all three gills rise in the M.-nilssoni 

 Zone, as will be seen from an examination of Table IV (p. 229). 

 Fossils are fewer than in the Narthwaite-Quarry beds ; but in the 

 third and largest gill they are well preserved and fairly abundant. 



Two exposures of a fine grey-green grit — one in the site of an 

 overgrown quarry near the summit of the hill overlooking Adam- 

 thwaite, and the other in the hillside above Narthwaite, probably 

 represent a higher horizon of the M.-nilssoni Zone. 



(b) The Ludlow Beds of Ravens tonedale Common. 



The beds, dipping in a general north-north-easterly direction, are 

 exposed in numerous streams flowing northwards and southwards 

 from the watershed, and in small quarries occurring in the hill- 

 sides. 



Spen Gill and Dale Gill. — The Lower Ludlow rocks are 

 well exposed in the higher part of Spen Gill, which flows southwards 

 from the Howgill watershed, and in Dale Gill flowing northwards. 



At the source of Spen Gill good specimens of Monographic 

 bohemicus and M. colonus were obtained in some abundance, from 

 a micaceous band of rock which weathered red ; and throughout 

 the upper part of the gill occasional fossiliferous bands are found 

 in the blue banded grits, yielding M. colonus and M. roemeri. 



Across the watershed small scree-slopes occur in the hillside of 

 Green Bell ; palaeontological evidence still points to the continuation 

 of the M.-nilssoni Zone (D x ), for graptolites of the colonus type pre- 

 served in relief are common. 



At the source of Dale Gill similar rock crops out ; but the 

 fossils are poor, and only preserved as impressions. The head of 

 Stwarth Gill has yielded Cardiola, Ortliis. and Pterincea ; and a few 

 badly preserved graptolites occur in a red grit which alternates 

 with red micaceous flags. 



Lower down the gill the rocks again change to blue-grey grits, 

 sandy beds with lamellibranchs and trilobites (Acidaspis), and 

 smooth unfossiliferous flags. No graptolites were found until 

 50 yards below the junction of Stwarth and Dale Gills, where a 

 highly fossiliferous blue band crops out at the bend of the river, 

 containing Monograptus leintwardihensis with many lamellibranchs 

 and trilobites. The beds dip at 36° east-north-eastwards. 



Gais Gill and Adamthwaite Road. — A small quarry 

 situated in Adamthwaite Bank, overlooking the right tributary of 

 Gais Gill, has yielded abundant specimens of Monograptus leint- 

 wardinensis, which tend to be preserved in relief in a hard, banded, 

 blue-grey flag. No further exposures occur until this tributary 

 joins with Long Gill, forming Gais Gill. Here the rock dips at 37° 

 north-north-eastwards ; it consists of coarse and fine red grits 

 alternating with flags in which M. hohemicus, M. colonus, and 



