144 CANADIAN FOSSILS. 
numbers, the stipes lying intertwined among themselves upon the surface 
of the shale. The cell-denticles are very minute; and near the base of 
the stipe the surface appears as if marked by small punctured or indented 
pustules. This pustuliform aspect seems to be due to the strong partition- 
walls of the cellules, which resist the pressure, and retain nearly their 
original form, while the adjacent parts become flattened. Farther from 
the origin of the stipe the whole substance is extremely compressed, and 
the cellules are only indicated by undulations in the margin of the stipe, | 
which show obscurely the rounded cell-denticle. The cellules are almost 
always upon the convex side of the curve of the stipe. 
The proportions of the stipe are about the same as in G. tenuis, Hall, 
(not Portlock) ; but that species has the stipes straight and extremely 
flattened in all the specimens seen. In both species the cell-denticles are 
rounded, or appear only as slight undulations of the margin; but in 
G. tenuis, the number in the space of an inch is from twenty-two to 
twenty-four. These, with the other differences, are very distinctive. 
EXPLANATIONS OF FiGuRES oF GRAPTOLITHUS FLACCIDUS, Hall. 
Prats II. 
17. A portion of a large fragment of slate, with parts of several individuals upon the 
surface, and showing the origin of eight individuals in the minute radicles. 
Some of these are indicated by asterisks on the engraving. 
18. An enlargement to three diameters of the radicle and stipe-bases, with the cellules. 
From the point @ on fig. 17. } 
19. A farther enlargement of a portion to show the form of the cellules, and the pustu- 
liform appearances at the base of the divisions between the cellules. 
formation and Locality.—Shales of the Utica formation; Lake St. 
John, east from Blue Point. 
GRAPTOLITHUS QUADRIMUCRONATUS, Hall. (a. s.) 
Plate XIII, figs. 1-10. 
Stipes consisting of simple quadrilateral tubes, which are celluliferous 
on the two opposite sides ; the plain and the celluliferous sides being of 
equal width im the middle, or half-way from the base to the apex, where 
the stipe attams its greatest dimensions; celluliferous sides of the stipe 
