Vol. 67.] SALOPIAN ROCKS OF CAUTLEY AND BAYENSTOUEDAXE. 231 



Cardiola interrupta are common. These fossils all indicate the 

 M.-nilssoni Zone. 



The gill flows practically on the strike cf these rocks as far as 

 the footbridge on the Adamthwaite Eoad. A small exposure of 

 typical hard, blue, banded Wenlock rock occurs here in the left 

 bank of the stream, and has yielded specimens of M. flemingii 

 var. a, which is a typical fossil of the G.-rigidus Zone. Beyond 

 this point, for a distance of 170 yards, no good exposure occurs 

 until a quarry on the Adamthwaite Road is reached, in which 

 fossils characteristic of the M.-nilssoni Zone are fairly numerous. 

 The rock is similar to that previously described in the upper part 

 of Gais Gill, and dips at an angle of 20° north-north-eastwards. 

 Beyond this quarry the surface is again hidden by vegetation, 

 until exposed in a cutting in the roadside, opposite a shed south of 

 Banks Farm, which again yielded M. leiatwardinensis. The rocks 

 dip 39° north-north-eastwards. This succession of zones, with the 

 rocks all dipping in a general north-north-easterly direction, seems 

 to point to isoclinal folding in this region. 



Isolated exposures. — The zones of Monograptus nilssoni and 

 M. leintivardinensis are seen in numerous other stream-sections, 

 but only a few present fresh, features of interest. 



Sfconely Gill and Two Gills rise in Harter Pell, and show large 

 exposures of Lower Ludlow rocks, which only differ from those pre- 

 viously described in their red coloration. M. bohemicus, M. colonus, 

 and M. rcemeri were found, in addition to Cardiola interrupta and 

 Orthoceras ; these fossils clearly indicate the zone of M. nilssoni (D T ). 

 The M.-leintwardinensis Zone (D ) was met with in Bowderdale 

 Beck and in Pinskey Gill, just north of Pinskey Bottom : the latter 

 locality yielded M. leintivardinensis and its variety incipiens ; these 

 two varieties have so far not been found together. 



IV. Correlation. 

 (1) The Wenlock Beds. 



A glance at Table V (p. 233) will serve to show that there is 

 abundant evidence in the Cautley area for a zonal classification of 

 the Wenlock Beds. Each of the four zones is clearly marked off 

 from the other three by a distinctive fauna ; also the fossils which 

 give their names to the zones are strictly limited to one zone, and, 

 with the exception of Gyrtograptus lundgreni, range through the 

 entire zone. 



We have preferred to retain C. lundgreni as the zone-fossil of 

 the highest Wenlock Beds, as Miss Elles has already chosen it for 

 beds of the same age in the Welsh Borderland. For purposes 

 of identification of the zone, however, the varieties of Monograptus 

 flemingii y & a have been most useful to us. 



