524 PROCEEDIXGS OP THE GEOLOGICAL SOCIETY. [JuXlC 17, 



of the fourth or fifth cellule, a gradual though slight contraction 

 then taking place, and continuing up to the distal extremity. In 

 other specimens, again, the frond is more decidedly fusiform, or lan- 

 ceolate-ovate, the cellules attaining their full maturity from about -^ 

 to 5 of an inch above the base ; whilst in others the shape is simply 

 ovate, the broadest part in all being just above the base. The distal 

 extremity, in the most unequivocal specimens, is terminated by a 

 straight non-celluliferous Hue. The axis is very delicate, and is 

 usually prolonged beyond the distal extremity of the frond, this 

 distal extension being often somewhat dilated. The common canal, 

 though very narrow, is undoubtedly present. The cellules average 

 30 in the space of an inch, but vary between 25 and 40 ; they are 

 inclined to the axis at an angle of from 30° to 45°, differing in dif- 

 ferent parts of the frond, are in contact for about two-thirds of their en- 

 tire length, narrow at their origin from the common canal, but widen- 

 ing out gradually towards the aperture, and, when well preserved, 

 marked in their outer half by numerous fine striae or lines of 

 growth which run parallel to the cell-mouths. The cell-mouths are 

 curved, and nearly at right angles to the axis of the cellules, their 

 lower lips being very usually prolonged into acute submucronate 

 tips, but not furnished with true spines. These submucronate den- 

 ticles are not observable in the figures of Barrande and Geinitz, but 

 they are present in most of our Enghsh specimens. That their pre- 

 sence or absence is not, however, of specific importance, but is 

 chiefly due to the state of preservation, is shown by the fact that 

 they are sometimes present in one portion and absent in another of 

 even the same specimen. 



The above characters, drawn chiefly from Dumfriesshire speci- 

 mens, combine to make up a very distinct species, which appears on 

 the whole to agree in all important points with the Gra2)toUthus 

 palmeus of Barrande. The specimens from the Coniston Flags, 

 though diff'ering in some minor particulars, cannot possibly be sepa- 

 rated from the above, as they agree in the possession of a blunt, 

 tapering radicular process, and in the very peculiar shape of the 

 frond. The cellules, too, have the same shape, and the same sub- 

 mucronate extensions from their lower margins ; but their number 

 is usually more than 40 in the space of an inch, and the entire 

 frond, as far as I have seen, does not attain a length of more than 

 half an inch, exclusive of the axis. 



Log. Coniston Plags of Skelgill Beck, near Ambleside. (Also 

 common and well preserved in certain localities in the Upper Llan- 

 deilo rocks of Dumfriesshire.) 



DlPLOGRAPSTJS FOLItTM, His. PI. XIX. figS. 4-7. 



Prionotus folium, Hisinger, Leth. Suec. Supp. t. 35. fig. 8. 

 Oraptolithus ovatus, Barrande, Grapt. de Boheme, pl. 3. figs. 

 8, 9. 

 Frond ovate, commencing at the base by a broad tapering trun- 

 cated radicular process, which is prolonged upwards into the 

 first two cellules. Length from -f-^ to -f^ of an inch; breadth 



