74 CANADIAN FOSSILS. 
the full proportions. In several specimens (and indeed in all those upon 
which the species was originally founded), the stipes diverge from the 
radicle at an angle of 15° or 20° with the celluliferous faces on the inner 
or approximate margins. A later examination of other collections shows 
some specimens where the divergence is greater, and the development of 
parts more excessive. 
Three individuals of this species from the shales at Point Lévis preserve 
very constant characters in the mode of growth and structural details. One, 
a single stipe much longer than the others from the same locality, pre- 
sents some departure from the prevailing characters, and is referred with 
hesitation to this species. Another specimen among later collections from 
above the river St. Anne, has more divergent stipes and a stronger form 
than those first described. In the imperfect condition of preservation of 
these specimens, it is not easy to determine what extent of variation in 
individuals of this form may be due to the mode of growth and to other 
causes. 
EXPLANATIONS OF FiGURES OF GRAPTOLITHUS BIFIDUS, Hall. 
Puate I. 
6. A small specimen from the same fragment of slate with fig. 17. 
17. An individual of ordinary size. 
8. An enlargement of the upper part of one stipe of fig. 17. 
Puate III. 
9. An individual of this species, having a greater divergence of the stipes than is 
usually observed. 
10. An enlargement from one of the stipes of the preceding, showing the form of 
serratures, and the minute pustules at the base of the cell-divisions. 
Formation and Localities.—Shales of the Quebec group ; Point Lévis, 
and three miles above the river St. Anne. 
4, GRAPTOLITHUS INDENTUS, Hall. 
Plate I, figure 20. 
(GRAPTOLITHUS INDENTUS, Hall: Geological Survey of Canada, Report for 1857, page 128.) 
Description.—Frond consisting of two simple stipes, diverging at the 
base from a slender radicle, and making an angle between the two of 50° 
for the first quarter of an inch, and above this continuing in a nearly par- 
