1868.] NICHOLSON C0NI8T0N-FLAQ GRAPTOLIXES. 537 



and belongs to the same natural subgroup ; but it is sharply sepa- 

 rated by the broad, tooth-like, close-set cellules, which have hardly 

 any interval between them, so that the celluhferous edge of the stipe 

 assumes a pectinated appearance. 



Log. Beautifully preserved in relief in the Coniston Flags of Skel- 

 giU Beck, near Ambleside ; also, of doubtful occurrence, in the 

 Upper Llandeilo rocks of Polmoody Burn near Moffat. 



Graptolites Nilssoni, Barr. PI. XX. figs. 16-21. 



G. Nilssoni, Barrande, Grapt. de Boheme, pi. 2. figs. 16, 17. 

 G. Nihsoni, Geinitz, GraptoHthen, pi. 2. figs. 19, 28, 31, & 32. 

 Monoyrapsus proteus, Geinitz, ibid. pi. 4. figs. 9, 10, 11, 12, 



15-18, & 20. 

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



%. 7. 

 G. intermedius, Carruthers, Geol. Mag. vol. v. pi. 5. fig. 18. 



Stipe long, linear, monoprionidian, of an average breadth of 

 from J^ to -^ of an inch. Axis capiUary. Common canal ex- 

 tremely slender. Cellules long and triangular, with pointed den- 

 ticles so arranged that the cell-mouth of each is situated exactly at 

 the commencement of the next. Cellules from 18 to 20 in the 

 space of an inch, very narrow, the ceU-mouth being nearly rectan- 

 gular to the axis. The " superior " wall of the cellule is, properly 

 speaking, absent ; the " inferior " margin is about twice as long as 

 the cell-mouth, or rather longer, inclined to the axis at from 20° to 

 30°, and usually slightly concave. The denticles are pointed, and are 

 occasionally somewhat deflexed. The base is curved and extremely 

 slender, the cellules appearing as little triangular protuberances on 

 the axis, but preserving the same characters as in the fully developed 

 portion of the stipe, being especially characterized by the short rec- 

 tangular cell-mouths, the acute, sometimes deflexed, denticles, and 

 the long, curved '' inferior " ceU-walls, which are inclined to the 

 axis at an extremely low angle. 



Yar. a. major, Nich. PL XX. figs. 20, 21. 



Stipe attaining a breadth in the fully developed portion of about 

 ■Jg of an inch. Common canal comparatively weU marked. Cellules 

 20 to 25 in the space of an inch, triangular, the cell- mouths form- 

 ing a more or less acute angle with the axis, though never departing 

 far from the perpendicular ; the inferior ceU-waU about twice the 

 length of the aperture, inclined to the axis at about 30°. The den- 

 ticles acutely angular and sometimes slightly deflexed. 



Var. /3. MINOR, Nich. PI. XX. figs. 16, 17. 



Stipe extremely narrow, being nothing more than a mere line, upon 

 which the cell-mouths appear as little varicose knots or ampulla- 

 tions. Cellules long, narrow, and remote, from 18 to 20 in the space 

 of an inch, so arranged that the cell-mouth of each is exactly at 

 the base of the next. CeU-apertures nearly rectangular to the axis. 



