C. La/pworth — On Scottish Monograptidce, 551 



Hawick beds, it becomes at once recognizable in several foreign 

 localities. 



A few of its commoner forms are met with in Thuringia, as at 

 Linda, Grafenwarth, etc., but the whole group is especially charac- 

 teristic of the Colonies of Mons. Barrande, and possibly of the 

 greater part of the band E. e. — 1, which he places at the base of 

 his Upper Silurian. In Sweden some of its species occur in the 

 higher beds of Dr. Linnarsson's Upper Graptolitic Schists (zone B. 

 of Table), almost at the summit of his Lower Silurian. In France 

 and Spain a few of the same forms have been detected in beds 

 believed to lie either at the summit of the Lower or at the base of 

 tlie Upper Silurian of those countries. 



Group C. — This is constituted by the Monograptidce occurring in 

 the Eiccarton Beds, and in the Lower Division of the Silurians of 

 the Pentland Hills. Its remarkable distinctness, as a whole, from 

 that derived from the Gala Series, owing to the unfossiliferous 

 nature of the intervening Hawick rocks, has already been sufficiently 

 insisted upon. Its peculiar forms in South Scotland are : Mono- 

 graptus colonus, Barr. ; var. dubius, Suess ; M. Bdccartonensis, 

 Lapw. ; M. Flemingii, Salter ; M. vomerinus, Nich. ; and Ci/rtograptus 

 Carruthersi, Lapw. 



Its unequivocal Upper Silurian character is clear from the fact 

 that its Graptolites are those of the Coniston Flagstones of the Lake 

 District, and of the strata of the Wenlock and Lower Ludlow for- 

 mations of Siluria. 



On a general review of the whole of the facts adduced in the 

 foregoing pages, it appears that we possess at the present time 

 sufficient evidence to justify us in accepting the following 

 generalizations. 



Of the numerous forms of Graptolites belonging to the family of 

 the Monograptidce afforded hj the Silurian rocks of the South of 

 Scotland, each has a certain definite restriction in the vertical series 

 of deposits. 



Further, the three successive rock-groups of Birkhill, Gala and 

 Eiccarton possess each a well-marked assemblage of Monograptidcd, 

 which is easily separated as a whole from that of the other formations. 



And finally, the general vertical succession of species and 

 varieties of the Monograptidce in these rocks is in complete accord- 

 ance with that in Ireland, Westmorland, Central Europe, and 

 Scandinavia. 



My obligations to Mr. W. A. Sanderson have been already 

 acknowledged. Of others to whom I am specially indebted for 

 assistance in these researches, the chief is my friend Mr, Jas. Wilson 

 of Edinburgh, by whom, or in whose company, the majority of the 

 forms figured were originally collected in the field. Prof. H. A. 

 Nicholson generously accorded me the valuable privilege of studying 

 his magnificent collection of English forms from the Lake District 

 and Siluria. Mr. W. Swanston, of Belfast, submitted for examination 

 all the species discovered by him in the Silurian rocks of County 



