Vol. 56.] FORMATION AND ITS GRAPTOLITE-FAUNA. 437 



graptolitiferous beds are seen, and at (7) they have yielded Mono- 

 graptus scanicus, M. chimcera, M. Boemeri, and M. dutyus. Above 

 these come hard, dark, calcareous flags, slightly micaceous, and with 

 a concretionary structure (8), which give rise to a waterfall 12 feet 

 high. They are a continuation of the flaggy mudstones (6) above 

 the M.-bohemicus shales seen in the road-section, and form a marked 

 feature all along the hill-range. They contain no graptolites and 

 but few fossils of any kind. These flags are succeeded by slightly 

 less flaggy beds, but still destitute of graptolites. Above the 1000- 

 foot contour (9) the stream-course rises more rapidly, and at (10) 



Fig. 7. — (Approximate scale : 6 inches = 1 mile.) 



.. „ . ... Aberedw-mil PenwaunPool 



N.N.W. ^^s^S^Sl5?555^^_ :5.S£ 



Tremaen ^^^^^^$^^ L t. ^^^£/JZ 



Quarry. ^^^^^^^ 



^gggllllP^ 1 ^ Section through Abere&w Hill from Tremaen 



.t-s^llfilll^ a/ • to Penwaun Pool- 



^^j§g|p5^'' U.L- Upper -Ludlow NL = Zone of M. Mlssoni. 



^8z^0^ V. Lt. * Zone of M.leintwardinensis.V. = • - M. vulgaris. 



^If^W.S. 5<?.= - ■ M. scanicus. W.S.-JVenLock Shales. 



occurs a band crowded with casts of Pentamerus Knightii. This is 

 followed by greyish-brown micaceous flags, splitting readily, which 

 have yielded several specimens of M. leintwardinensis. At (11) 

 dark calcareous flags come in, as at (8), barren of fossils, inter- 

 stratified with calcareous bands crowded with brachiopods (mainly 

 Dayia navicula), corals, crinoid-stems, etc. At (12), farther north, 

 are dark calcareous flaggy beds with abundant fossils, and on one 

 slab Pentamerus Knightii occurs in association with Monograptus 

 leintivardinensis. At (13) light-brown mudstones contain bands 

 almost entirely composed of the casts of Pentamerus Knightii, 

 Dayia navicula, corals, polyzoa, etc. 



It would appear, therefore, from this section that it is impossible 

 to draw any palaeontological line between the Lower Ludlow Beds 

 and the representatives of the Aymestry Limestone, for the graptolite 

 (M. leintwardinensis) characteristic of the highest zone of the Lower 

 Ludlow occurs in association with brachiopods, such as Pentamerus 

 Knightii, which are typical elsewhere of the Aymestry Limestone. 

 Consequently, the evidence obtained in this Aberedw area confirms 

 the conclusion previously arrived at from a study of the corresponding 

 rocks in the typical district of Ludlow, namely, that the Aymestry 

 Limestone should be regarded as part of the Lower 

 Ludlow formation. 



Other small exposures are seen at various points along the hill- 

 side. One good section through the lower beds of the M.-scanicus 

 xone and the comparatively unfossiliferous shales below is visible in a 



