80 CANADIAN FOSSILS. 
side of the specimen, as if the cellules had been turned downwards ; but } 
this appearance is fallacious. In examples where the radicle is broken from 
the margin of the stipe, the question is suggested whether it may have been 
a quadribrachiate species; but the pointed radicle in others is opposed 
to the supposition. In the specimens from which this description is drawn, 
there are several examples of two individuals lying with the celluliferous 
margins nearly or quite in juxtaposition ; while the stipes crossing each 
other at a distant point may give an erroneous impression regarding their 
mode of growth. 
On a cursory examination of the specimens before us, this species is 
readily identified by the peculiar curving of the stipes; differing in this 
respect from all the bibrachiate forms which have been observed. In the 
form of the denticles, or free portions of the cellules, this species approaches 
G. patulus ; but these parts are less mucronate, and the angle between the 
axis and the cellules in that species is much greater, and the cellules are 
narrower. The general form of stipe, except in its peculiar curvature, 
does not differ essentially from some others previously described ; but a 
comparison of the form of the cellules, their proportionate dimensions, and 
angle of inclination, will suffice to show its distinctive character. 
EXPLANATIONS OF FiguRES OF GRAPTOLITHUS ARCUATUS, Hall. 
Puate II. 
6. A stipe of a small individual, more than usually curved. 
7. A stipe having a process just above and opposite the radicle. 
8. A larger stipe, the cellules very clearly preserved. 
9. A specimen showing the stipes on both sides of the radicle, and preserving their 
peculiar curvature very perfectly. 
10. An enlargement of a portion of one of the stipes. 
Formation and Locality.—Shales of the Quebec group ; Point Lévis. 
9. GRAPTOLITHUS EXTENSUS, Hall. 
Plate II, figures 11-16. 
(G. extensus, Hall: Geological Survey of Canada, Report for 1857, page 132.) 
Description.—Frond consisting of two simple linear very slender 
stipes, which diverge at right angles to the direction of the minute radicle, 
and lie in the same plane. Stipe near the radicle one fiftieth of an inch 
in diameter, and at a distance of four inches from the radicle, one tenth of 
