GRAPTOLITES: #23 
EXpPLANATIONS-OF Figures oF PHYLLoGRapPTUS ILIcIFoLIUs, Hall. 
Pratt XVI. 
1. An individual of the natural size, where the folia 6, a* are broken entirely 
away beyond the axis, leaving the bases of the cellules of two adjacent 
folia visible except at the upper part of the figure, where two or three of 
the bases of the other cellules remain. 
2. A similar specimen, showing the bases of a set of cellules on each side of the 
centre, with two or three of those belonging to the broken folium at the 
base of the figure. 
3. An enlargement of fig. 2, showing more distinctly the cellules on each side 
of the central line, and the small remaining portion at the base. 
4. A specimen of the natural size, where one folium is broken away not quite 
so far as the axis, leaving the bases of its cellules visible. 
5. An enlarged figure from a specimen which has been imbedded transversely. 
Three of the divisions have been broken away, leaving impressions of the 
lateral ones only, and of the cell-bases, and cell-partitions of the fourth 
division, which are directed obliquely upwards from the axis and point of 
view. The lower part of the specimen preserves a portion of the lateral 
folia, with the bases of the cells of the outer division a*, which are directed 
towards the axis. 
6. An enlargement of a specimen which is imbedded obliquely, or in a direc- 
tion as if the theoretical figure 10 were vertically compressed, leaving 
no visible axis. In the lower half of the specimen, the fossil has been 
separated in the opposite slaty lamina, leaving only the impression of the 
opposite side, which also shows no axis. Inthe upper half of the specimen, 
the cellules are well preserved, and on the left-hand side the apertures are 
conspicuous. Enlarged to three diameters. 
It will be observed that the impression is not quite in the same direction 
as the outline in theupper portion of the figure, owing to the obliquely- 
compressed folia. 
7. A specimen compressed in the same manner.as fig..6; the upper folia have 
however been separated, except the bases. of a few of the cellules in the 
upper part of the figure, leaving the other two folia imbedded in the shale, 
and showing the bases of their cellules ascending from the axis. Enlarged 
to three diameters, as in fig. 6. 
$. Anenlarged figure of a specimen compressed in the direction first described, 
without any separation of the. parts; from which cause there is no proper 
axis visible. In this condition, thespecimensresemble Graptolithus folium 
of Hisinger, or G. ovatus of Barrande. 
9. An enlargement of a specimen. compressed as in fig. 8, but with the cellules 
filled, and the margins of the upper two folia broken, showing the cell- 
Openings. (8 and 9 are enlarged to twice their natural size.) 
10. A restoration of the form of P. ilicifolius, showing the four divisions; which 
are represented as cut through transversely, exhibiting the cell-cavities. 
Formation and Locality.—Quebec group ; Point Lévis. 
* These letters refer to the illustrative figures on page 119. 
