EXPLANATIONS OF PLATE A. 
CLIMACOGRAPTUS TYPICALIS, page 57. 
See observations on C. (G.) bicornis, etc., pages 27, 28, 30, 45, and 111. 
Figures 1—8 are enlarged to six diameters. 
Fig. 1. A lateral view of the concave side, with the surface entire, showing the form of 
‘the cell-apertures. ‘ 
«2. A lateral view of the same, showing the entire form of the cell-apertures. 
“¢ 3. Lateral view of a fragment where the surface is exfoliated, showing the cell- 
partitions extending downwards towards the centre. 
“ 4, A longitudinal section made a little below the exterior surface, showing the cell- 
partitions extending further towards the interior than in fig. 3. 
“ 5, A longitudinal section through the centre, showing the cell-partitions reaching 
to the central axis. 
“« 6. A transverse section, showing the cell-partitions just within the aperture, and 
the minute central axis. 
“¢ 7. A transverse section made a little lower than in fig. 6, showing the cell-partitions 
extending across the stipe on one side, and on the other side showing the 
narrow triangular point near the centre. 
“ 8. A section made diagonally across a crushed stipe, showing the folding (from 
pressure) of two cell-divisions on each side of the centre. 
““ 9. An ideal longitudinal section, showing the form and direction of the cell-parti- 
tions and the central axis, (enlarged to twelve diameters). 
GRAPTOLITHUS PUTILLUS, pages 27 and 44, 
Enlarged to twelve diameters. 
Fig. 10. A fragment of a stipe, showing the two ranges of cellules, their form, mode of 
growth, and the unfolding of the exterior test along the line of the central 
axis. 
‘ 11. A lateral view of the same fragment, showing the cell-apertures and the flat- 
tening of the exterior of the base of the next cellules in advance, and the 
greater breadth of the cellules at the bases. 
“ 12. A longitudinal section through the centre of the stipe, showing the double 
cell-partitions and the double central axis. 
“ 12 a. A transverse section cutting one cellule near the aperture and the other near 
the base. 
CLIMACOGRAPTUS BICORNIS, pages 20, 21. 
(Graptolithus bicornis, Paleontology of New York, vol. i, page 268, and Geology of 
Canada, page 200.) 
Fig. 13. The lower part of a stipe enlarged to two diameters, showing the bifurcating 
process and a central node or radicle. 
“ 14, An enlargement to six diameters of a fragment which preserves in a very per- 
fect manner the bozder of the cellules, and shows an undulating central 
axis as well as the median ridge. 
«15. The base of a specimen showing three spine-like processes, (two diameters). 
“ 16. The lower extremity of a specimen showing a partially developed corneous 
disc, (two diameters). 
11. The lower extremity of another specimen, showing a more complete disc or 
bulb at the base, (two diameters). 
