542 PROCEEDIXGS OP THE GEOLOGICAL SOCIETY. [June 17, 



basal portion extremely narrow, but the cellules differ entirely from 

 those of the adult stipe, being, in fact, undistinguishable in all their 

 characters from those of the smaller forms of G. Wihsoni, Barr. 

 The solid axis is slender and cylindrical, and in young specimens is 

 often seen to be prolonged beyond the distal extremity of the stipe. 

 The common canal, except in very young individuals, is suflGlciently 

 well marked. The cellules are inclined to the axis at about 45°, 

 averaging about 2h in the space of an inch, but varying in number 

 from 20 to 30. The cell-mouths are at right angles to the axis, each 

 encroaching slightly upon the cellule immediately above ; the den- 

 ticles are angular, and rarely furnished with minute spines. The cel- 

 lules overlap one another for from one-third to one-half of their entire 

 length, the free portion being often somewhat the widest, and having 

 a dilated and sacculate appearance. 



G. Sagittarius, Linn., is apparently exclusively confined to the 

 Lower Silurian rocks, in Britain certainly, and probably abroad 

 as well. It is of very doubtful occurrence in either the Skiddaw 

 Slates or the Lower Llandeilo rocks proper, but it is a highly 

 characteristic and abundant fossil in both the Upper Llandeilo 

 and the Caradoc groups. It is found in tolerable plenty- in the Coni- 

 ston Flags, and it appears to have survived into the Coniston Grrits. 



Log. Coniston Flags of Mosedale in Long Sleddale and Skelgill 

 Beck, near Ambleside ; Coniston Grits of Helmside, near Dent (?). 



Graptolites tttreiculatus, Barrande. PL XX. figs. 29, 30. 



Stipe simple, monoprionidian, and coiled up into a conical spire 

 which does not lie in one plane, but is " trochoid " or inequilateral 

 in form. The base commences by an obtusely pointed radicle. The 

 solid axis is well marked, and the common canal is, comparatively 

 speaking, of considerable breadth. The cellules are about 45 in the 

 space of an inch, triangular, pointed, and curved, their apices being 

 somewhat reflexed and provided with small spines. 



G. turricvlatus, Barr. (perhaps the most elegant species of the 

 entire genus) , has not hitherto been detected out of Bohemia ; but I 

 have been fortunate enough to discover several specimens of it in 

 the Coniston Flags. The form is one that cannot possibly be con- 

 founded with any other yet described, being immediately distin- 

 guished by the helicine curvature of the stipe, and by the close-set, 

 curved, mucronate denticles. 



Loc. Coniston flags of Mosedale in Long Sleddale. 



Correlation of the Coniston Flags ivith foreign deposits. 



By way of conclusion to this paper it may be as well to make a 

 few remarks on the correlation of the Coniston Flags with the Grap- 

 tolitiferous rocks of Bohemia and with the Utica Slates of America. 



According to Barrande, there are in Bohemia two zones in which 

 Graptolites occur — one (etage D) at the summit of the Lower Silu- 

 rian, and the other (etage E) at the base of the Upper Silurian 

 division, the two being separated by a series of trappean rocks. In 

 the former or lower zone occur G. priodotr, Bronn, G. Bohemicus, 



