1808.] NICHOLSON CONISTON-FLAG GRArXOLITES. 625 



nearly ^ of an inch. Axis capillary, sometimes prolonged beyond 

 tlic distal extremity of the frond. Common canal narrow. Cellules 

 inclined to the axis at about 40° in the middle of the frond, 

 but becoming nearly vertical towards its distal extremity, the last 

 cellules being nearly parallel with the axis. The cellules are in all 

 respects similar to those of D. palmeus, Barr., being narrow at their 

 origin from the common canal, but widening out towards the cell- 

 aperture, slightly curved, and marked in their outer half with 

 numerous fine curved striae running parallel with the cell-apertures. 

 Most specimens exhibit from 40 to 50 cellules in the space of an 

 inch, so that the smaller examples do not contain more than 10 cel- 

 lules on each side. 



The above description is drawn from several specimens which I 

 obtained from the Coniston Flags ; and though differing in some 

 respects from what has been usually figured as D. folium, His., I 

 am unable at present to place them under any other species. At 

 the same time I am strongly of the opinion that (whichever name 

 may be ultimately retained) I), fol'mm, His., will eventually turn 

 out to be nothing more than a variety or a young form oi D. paJmeuSy 

 Barr., most probably the latter. The two agree exactly in the 

 shape of the cellules and in the characters of the radicular process ; 

 whilst the only diff'erence of any moment is to be found in the fact 

 that D. folium, His., terminates distally in a rounded celluliferous 

 margin, while D. palmeus, Barr., has the same extremity bounded 

 by a straight non- celluliferous line. Graptolitlius ovatus of Barrande, 

 appears also to be a young form of D. palmeus, and it is, at any 

 rate, inseparable from what I have here described as D. folium, 

 His. 



Loc. Coniston Flags of Skelgill Beck, near Ambleside. 



DrPLOGRAPSTJS ANGTJSTrFOLIUS, Hall. PL XIX. figs. 8, 9. 



Graptolithus angustifolius. Hall, Pal. N. York, vol. iii. p. 515. 



Frond simple, and diprionidian. Breadth a little short of one 

 line. Cellules from 28 to 30 in the space of an inch, subalternate, 

 or nearly opposite to one another, " the denticles short, ovate - 

 acute, the extremities sometimes subobtuse" (Hall). The com- 

 mon canal is very slender, and the axis is prolonged beyond the 

 distal extremity of the frond. According to Hall, the base "■ is 

 marked b}^ minute setiform radicles." 



I have found one example of this species, exquisitely preserved in 

 relief, in the Graptolitiferous mudstones of SkelgiU Beck, and there 

 can be no question of its identity with the American form. As D. 

 angustifolius, Hall, has been recently confounded with D. acumi- 

 natus, Nich. (Carruthers, Geol. Mag. vol. v. p. 130), I may here 

 mention that no two species of the genus Diplograpsus arc separated 

 from one another by better-marked distinctions. In D. angusti- 

 folius. Hall, the base is marked by *' minute setiform radicles " 

 (one or more in number), whilst the cellules are subalternate, are 

 from 28 to 30 in the space of an inch, and possess extremities which 

 are usually rounded off and obtuse. In JD. acuminatiis, Nich., on 



