GRAPTOLITES. 119 
tion, as in fig. 2. In-this way, from the accumulation of the sediment, 
they would become compressed, as in fig. 3, until the parts 4, d,and a, 
e would approach each other, or come in contact. Lying thus, with 
the slaty laminze separating above or below them, they would present the 
aspects of figs. 6 and 9, pl..xv ; and of fig. 8, plate xvi. 
2 3 
1 
; a 
d) d 
ec 
‘ ad e 
d 
When the parts 6, are removed, the parts d, ¢ remain, showing the 
base of the cellules, as in figs. 4 and 5, pl.-xv, and figs. 3 and7, pl. xvi; 
while in the examples where the margins only are removed, we have 
appearances like fig. 9, pl. xvi. 
PHYLLOGRAPTUS TyPuUS, Hall. 
Plate XV, figures 1-12. 
(PHYLLogRApTus TyPUS: Geological Survey of Canada, Report for 1857, page 137.) 
Description.—Stipes robust, composed of four semi-elliptical parts joined 
by their straight sides. As preserved upon the shale, these bodies are 
elongate-ovate or lanceolate, broad oval or obovate : cellules about twenty- 
four, rarely twenty-two, and sometimes twenty-six in the space ofan inch, 
usually obscure at the margin ;.axis. or mid-rib broad, often-crenulate or 
serrate ; radicle usually short; im some specimens about half an inch in 
length being preserved. 
The stipe origimates from.a slender-pointed. radicle. The cellules near 
the base are short, coming out almost rectangularly to the axis, or slightly 
ascending and gradually increasmg in width, curving backwards or down- 
wards, and having the aperture sometimes nearly at right angles to the 
axis : the curvature lessens towards the middle of the stipe, and the line of 
aperture is parallel to the axis ; while above this they are inclined towards 
the axis, and near the summit they are again nearly at right angles to the 
axis, but opening in a direction opposite,.to. those, near the base. « Cell- 
