1868.] NICHOLSON — CON I8T0N. FLAG QHAPTOLITES. 541 



and also in some parts of the Coniston Flags, certain small Graptolites 

 which are decidedly distinct from O. 'priodon, and which, though 

 they differ somewhat from the typical form of G. colonus, Barr., 

 nevertheless appear to be really inseparable from it, and to be iden- 

 tical with one of the forms figured by Barrande (loc. cit. pi. 2. 

 fig. 5). 



Stipe simple, monoprionidian, from | to | of an inch in length, 

 attaining a breadth of about one line in the fully developed 

 portion, and tapering gradually towards the base. The base is 

 straight, and not curved, and is simply pointed, there being no 

 proximal extension of the solid axis. The back of the stipe is often 

 somewhat convex. The axis is capillary, and is prolonged for a 

 short distance beyond the distal extremity of the stipe. The cellules 

 are from 30 to 35 in the space of an inch, inclined to the axis at 

 about 45°, straight, free for about one-third of their entire length ; 

 the cell-mouths are curved, nearly at right angles to the direction of 

 the cellules, the proximal lip of the aperture being prolonged into 

 a submucronate extension, without, however, any true spines. 



The specimens from the Coniston Flags occur chiefly in the 

 *' sheer-bate" beds at the top of the series. They are too imper- 

 fectly preserved to admit of accurate determination, but they agree 

 with the specimens of G, colonus, Barr., from the Ludlow rocks in 

 the following points : — 1st, in the general form of the stipe, which 

 is from | to | of an inch in length, is slightly convex along the 

 back, and tapers gradually towards the base without curving up ; 

 2ndly, in the prolongation of the solid axis beyond the distal end of 

 the stipe ; and, 3rdly, in the existence of submucronate denticles. 



Loc. Coniston Flags of Skelgill Beck (grey grits above the mud- 

 stones), Horton in Ribblesdale, Broughton Moor, and Ash Gill 

 (cleaved flags), Torver Beck near Torver (" sheer-bate " flags) ; 

 Coniston Grits of Casterton Low Fell, near Kirkby Lonsdale. Abun- 

 dant in the Lower Ludlow rocks of Bow Bridge, near Ludlow. 



Graptolites sagittakius, Linn. PI. XX. figs. 25-27. 



Prionotus Sagittarius, Hisinger, Leth. Suec. Supp. p. 114, t. 35. 



fig. 6. 

 G. Barrandii, Scharenberg, XJeber Grapt. t. 1. figs. 5-7. 

 G. virgulatus, ibid. loc. cit. figs. 8-11. 

 G. nuntius, Barrande, Grapt. de Boheme, pi. 2. fig. 6. 

 G. incisus, Harkness, Quart. Journ. Geol. Soc. vol. vii. pi. 1. 



fig. 8. 

 G. Hisingeri, Carruthers, Geol. Mag. vol. v. p. 126. 



Stipe of unknown length, and varying in breadth from -^ to 

 J^ of an inch, commencing with a long and slender radicle, pro- 

 longed into an extremely slender, usually more or less curved, cel- 

 luliferous stipe, which gradually widens out and becomes straight. 

 The delicate basal portion of the stipe may sometimes be as 

 much as IJ inch in length before the cellules become fully 

 developed and assume their normal characters. Not only is this 



