314 C LAPWORTH ON THE MOFFAT SERIES. 



great majority of the beds of the zone, preserved them from 

 alteration or disturbance, and placed them in such a position that 

 every bed admits of thorough examination. The white bands are 

 here strictly confined to the higher half of the section, the beds of 

 the lower subdivision agreeing in all essential respects with those of 

 the underlying zone. The fossils are given in the following list : — 



Leptograptus flaccidus {Hall). 



capillaris (Carr.). 



Amphigraptus divergens (Hall). 

 Pleurograptus linearis (Carr.). 

 Dicellograptus elegans (Carr.). 

 Morrisi (Hopk.). 



Dicellograptus pumilus (Lapw.). 

 Climacograptus tubuliferus (Lapw.). 

 Diplograptus foliaceus (Murch.). 



quadrimucronatus (Hall). 



Retiolites fibratus (Lapw.). 

 Lingula, sp. 



Climacograptus tubuliferus is restricted to the lowest portion of 

 the zone as here exposed, which is also distinguished further by the 

 exclusive presence of Dicellograptus elegans (Carr.). 



In Dobb's Linn the strata of this zone may be followed almost 

 continuously from the southern boundary of the Main Cliff to a 

 point at the head of the Middle Score. The central bands, with 

 Pleurograptus linearis, are entire, and yield well-preserved fossils 

 where they are exposed in the Main Cliff; and all the species 

 occurring in the beds at Mouut Benger have been collected above 

 the Middle Score. 



At Hartfell the beds of this zone are exposed, and are highly 

 fossiliferous at several points in the north slope. Above the " cor- 

 nice," the central beds, here cut off from the succeeding strata by a 

 small fault, are filled with excellent examples of Pleurograptus 

 linearis and its associates. The higher beds, with their included 

 white and cream-coloured seams, occur again and again in the 

 numerous scores that furrow the slope beyond. 



These pale-coloured bands become very numerous in the bands 

 above St. Mary's Loch. At Fall-Law Score, Yellow Mire, &c. they 

 appear to have coalesced into a thick bed of soft white mudstone. 

 In the sections of the Moory Syke, Craigmichan, and Belcraig, the 

 underlying fossiliferous bands are more prominently exhibited, and 

 yield occasionally, when less altered than usual, a few of their 

 characteristic Graptolites. 



Everywhere this well-marked zone is characterized by the exclu- 

 sive presence of the peculiar compound genus Pleurograptus, which 

 has never yet been detected in any of the fossiliferous strata above 

 or below. Here also do we find for the last time the genera Lepto- 

 graptus, Amphigraptus, and Dicranograptus, and several species 

 belonging to other genera — Diplograptus foliaceus (Murch.), Dicello- 

 graptus Morrisi (Hopk.), D. elegans (Carr.), Climacograptus tubuli- 

 ferus, &c. 



(b) Upper Hartfell. 



The peculiar white or grey seams so prevalent in the upper 

 portion of the preceding zone finally exclude all trace of the asso- 



