230 REPORT ON THE STATE CABINET. 



and with double ranges of cellules, the mucronate or setiform extensions 

 are usually from the lower extremity of the cell-aperture, as illustrated 

 in fig. 30. 



In all those forms of which G. hicornis may be regarded as the type, 

 Fie 30. these processes, when existing, are extensions of the test above 

 I the aperture, so far as observed (Plate ii, figs. 1 and 9) ; or as in 



\ species of the character of fig. 20, Plate ii. 



In some species of Diplograptus there is a single mucronate 

 extension from the lower side of the cell aperture, as in the 

 ^\, accompanying illustration, fig. 30, of Gmptolithus (Diplograptus) 

 ^ whitjieldi, twice enlarged. 



In others, as G. quadrimucroiiatus (Plate iii, figs. 1 and 2), there 

 is a mucronate point extending from each of the lower lateral 

 angles of the cellules ; as also in G. testis of Bareande ; except 

 that in the Canadian species these appendages are more rigid. 



In Pliyllograftus typiis and P. ilicifolius, these processes are 

 apparently the extension of the angles of the cell-partition. 



The cellules of Dendrograptus, Callograptus and Dictyo- 

 NEMA sometimes show mucronate extensions from their outer 

 margins. In Retiolites the cellules sometimes terminate in a 

 plain margin, and in one species the divisions are extended in short 

 strong mucronate points (Plate i, figs. 5 and 21, and Plate iv, fig. 11). 



All the species of Retiograptus have the margins of the stipes gar- 

 nished with slender mucronate points, corresponding to the cellules, and 

 extending almost rectangularly to the axis (Plate iv, figs. 8 and 9). 



These ornaments are not always uniformly develojjed in the same 

 species or even in the same individual. In the larger proportion of 

 specimens of G. ramosus, the margin of the cellules are apparently plain ; 

 but in the cellules of the simple part of the stipe we sometimes find a 

 rigid mucronate point, prolonged from the upper margin or limit of the 

 cell-aperture (Plate ii, fig. 20). In G. sextans, the mucronate point is half 

 way between the two cell-apertures. 



In specimens of G. sextans, and in some allied forms from the Hudson 

 River formation at Marsouin, Canada East, the stipes and cellules are less 

 fully developed than' in those of the same species from Norman's Kill, 

 near Albany, while the mucronate extensions from the cell apertures are 

 more conspicuous. 



Besides these ornaments, there is on each side of the radicle or initial 

 point at the base of most of the diprionidian species of Graptolites, a 



