C. LAPW0RTH ON THE MOFFAT SERIES. 



325 



beautiful specimens of which occur in abundance. The peculiar 

 double black seam of the lower division of the zone also occurs in a 

 corresponding position at Thirlstane Burn, retaining fully its mine- 

 ralogical characteristics and its distinctive fossils. 



The best section of the beds of the M.-spinigerus zone is that of 

 Eldinhope Burn in the valley of the Yarrow, where every seam is 

 capable of exact admeasurement. It will be seen from the accom- 

 panying diagram how perfectly the beds at this spot agree with the 

 preceding description. The double seam with. Monograptus Cling ani 

 (Carr.) forms the base of the section, and the overlying beds of 

 barren shales are more than a foot thicker than at Dobb's Linn 

 (fig. 31). 



Fig. 31. — Zone of Monograptus spinigerus (Nich.). (Mdinhojpe 



Bum.) 



Greyish-green shales 



Black flaggy shales, concretionary, 

 flocculent or ashy white on edges ... 



Ashy or finely laminated muds and 



clays 



Black shales, hard, flaggy 



White seams 



White flaky shales 



Soft greyish-green shales, 6 ft 



Seam of fossils (3Ionograptus~Clingani 

 bed?), concretions, &c 



Few 31. spinigerus, Diplograptus 



Hughesi. 

 Crowded with Monograptus spinigerus, 



M. Hisingeri, 31. tenuis. 

 Monograptus tenuis. 



Crowded with Monograptus tenuis, 

 31. Hisingeri, &c. 



31. Halli (vars.), 31. Beehi, B. folium-, 

 &c. 



Monograptus Clingani. 



Beds belonging to this zone are visible also in Thirlstane Score 

 (fig. 8, p. 269), Biskinhope, Muckra, Duffkinnel, &c. Everywhere they 

 yield fossils of the list given above and none other. Everywhere, 

 from Sundhope to Glenkiln, the seam of soft pyritous mudstone 

 affording the spinose variety of M. spinigerus is the most prolific 

 stratum, swarming with innumerable Graptolites in admirable con- 

 servation. 



iii. Zone o/Rastrites maximus( Carr.). — The concluding zone of the 

 Moffat Series embraces the final 25 feet of shaly strata seen in the 

 typical exposure at Dobb's Linn. Its fossils are restricted to what 

 may conveniently be termed two pairs of black beds, separated by 

 three feet of barren shale. The lowest bed is nearly two feet in 

 thickness, the second about a foot, the third a few inches, and the 

 fourth a mere line. The zone contains many of the white-clay bands, 

 and the strata immediately in contact with the fossil beds weather 

 of a bright yellow colour. 



