PLATE III. 



DiPLOGEAPrns quadrimvcronatus, Hall. 



Fig. 1. Enlargement of part of a stipe compressed in a slightly oblique direction, still showing 

 the cellules on the two sides. 

 " 2. Enlargement of a stipe compressed more obUquely, so as nearly to obscure the cellules 



on one side. 

 " 3. Enlargement of a specimen compressed vertically to the celluliferous sides of the stipe. 

 " 4. A diagram representing a theoretical longitudinal section. 



" 5. A diagram representing a transverse section of a stipe, with the mucronate extensions 

 of the cell-margins. 



t 



DiPLOGRAPTUS A3IPLEXICAULE, HaLL. 



Fig. 6. Enlarged view of the back of a portion of a stipe, showing the form and direction of the 

 cells . 

 " 7. Enlargement of the inner face, showing the curvature and overlapping of the cells and 

 the quadrangular apertures. 



Graptolithus nitidus. Hall. 



Pig. 8. A large specimen, showing the radicle and two stipes, and the pustules at the base of the 

 cellules. The extremities are not quite entire. 

 " 9. A well preserved small individual, enlarged to three diameters. 



Oraptolithus flaccidus. Hall. 



Fig. 10. An enlargement, to three diameters, of the radicle and stipe bases with the cellules. 

 " 11. Afui'ther enlargement of a portion, to show the form of the cellules and the pustuliform 

 appearance at the base of the divisions between them. 



Graptolithus bxtensus, Hall. 

 Fig. 12. An enlargement of a fragment of a stipe, where the cellules are distended by iron pyrites. 



GRAPTOLPrHUS BIFIDUS, HaLL. 



Fig. 13. An individual of ordinary size. 

 " 14. An enlargement of one of the stipes of another individual, showing the form of serratures, 

 and minute pustules at the base of the cell divisions. 



Graptolitbus feuticosus. Hall. ' , 



Fig. 15. An enlargement of one stipe, with the bases of the other three, showing the form of 

 cellules and mode of bifurcation in this species. 



Graptolitbus bryonoides. Hall. 



Fig. 16. An enlargement of the base of a specimen, showing the initial point, the cell-denticles 

 on one of the stipes, and a proportionately longer funicle than usual. 

 " 17. An enlargement of a young individual, showing the initial point, funicle, and origin of 

 the four stipes, with a few of the earlier cellules. 



