PLATE II. 

 Climacooraptus typicalis, Hall. 



Figures 1-8 are enlarged, to six diameters. The specimens have the common caTial filled with mineral matter, so that 

 they are fully distended, except fig. S, which is partially flattened by compression. 



Fig. 1. A lateral view of the concave side, with the surface entire, showing the form of the cell- 

 apertures. 

 " 2. A profile 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 ceU-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 httle lower than in flg. 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-partitions and 



the central axis (enlarged to twelve diameters). 



DiPLOGRAPTUS PUTILLUS, HaLL. 

 Pigures enlarged to twelve diameters. 



Fig. 10. A fragment of a stipe, showing the two ranges of cellules, their form, mode of growth, 



and the infolding of the exterior test along the hue of the central axis. 

 " 11. A lateral view of the same fragment, showing the cell-apertures, the flattening 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. 

 " 12a A transverse section, cutting one cellule near the aperture, and the other near the base.. 



Cluiacograptvs bicornis, Hall. 



(■GraptoUthus bicornis, Palaeontology of New York, Vol. i, page 268, and Geology of Canada, page 200. J 



Fig. 13. The lower part of a stipe, enlarged to two diameters, showing the bifurcating process 



and a central node or initial point. 

 " 14. An enlargement (to six diameters) of a fragment which preserves in a very perfect 



manner the borders 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). 

 " 17. The lower extremity of another specimen, showing a more complete disc or bulb at the 



base (two diameters). 



