234 MISS G. R. WATXEY AND MISS E. G. WELCH ON THE [May I9II, 



(2) The Ludlow Beds. 



We have been able to distinguish two zones only in the Howgill 

 Pells, those of Monograptus nilssoni and 31. leintwardinensis : the 

 watershed of the Howgill area is occupied by rocks which are so 

 unfossiliferous that the evidence obtained from that region is in- 

 sufficient to permit the establishment of any zone. We have, 

 therefore, included it in the upper part of the M.-nilssoni Zone. 

 It may possibly represent the M.-scanicus and M.-tumescens Zones 

 found by Mrs. Shakespear in Wales and the Welsh Borderland. 

 It is of interest to note that 31. bohemicus is a far more charac- 

 teristic fossil of the first zone than M. nilssoni. The similarity 

 between this area and the Lake District has already been pointed 

 out (p. 228). 



Table VI. — Correlation of the Salopian Rocks. 



Gautley. 



Welsh Borders. 



Southern Sweden. 



Zone of Monograptus leintwardinensis. 



Zone of 31. leintwardinensis. 





Grits and flags \ ?= 



Zone of 31. tumescent. 

 Zone of 31. scanicus. 



Zone of 3Ionograptus nilssoni. 



Zone of 31. nilssoni. 



Zone of Phacops obfusicaudatus. (?) = 



Zone of 31. vulgaris. 



Zone of Cyrtograptus lundgreni. 



Zone of G. lundgreni. 



Zone of G. carrutliersi. 



Zone of Cyrtograptus rigidus. 



") Zone of C. rigidus. ( 

 > Zone of C. linnarssoni. \ 

 3 Zone of G. symmetricus. f 



Zone of C. rigidus. 



Zone of 31. riccartonensis. 



Zone of Monograptus riccartonensis. 



Zone of 31. riccartonensis. ) 



Zone of Cyrtograptus murchisoni. 



Zone of G. murchisoni. 



Zone of C. murchisoni. 



V. Palaeontology. 



Cyrtograptus rigidus, Tullb. (figs. 2 & 3, p. 235). 



Our specimens of this Cyrtograptid are intermediate in form 

 between 0. rigidus and C. symmetricus ; we find that the branching 

 almost invariably occurs at the seventh or eighth theca, and that the 

 first nine thecce are of the proximal type : these characters constitute 

 a slight divergence from both G. rigidus and C. symmetricus. 



Several specimens show prolongation of the virgula in both 

 branches. It has seemed best, however, to adhere to the name 

 first given by Tullberg, since in general form our specimens agree 



