196 TWENTIETH REPORT ON THE STATE CABINET. 



There are cellules, however, where the production of the calycle by 

 budding from the common body is not so obvious. These forms are like 

 G. bicorjiis and G. antennarivs, where the orifice is a simple transversely- 

 oval aperture in the side of the stipe ; and in the flattened specimen, it appears 

 like a rectangular or slightly oblique semi-oval notch in the margin. Its 

 true form is perceived only when the cavities of the polyp have been filled 

 with mineral matter, or when the stipes are flattened vertically against the 

 apertures : they then give the form which has been described as G. scalaris. 

 This form of cellule is sliown on Plate ii, figures 1 and 2, which are 

 enlarged from a specimen retaining nearly its original proportions. Just 

 within the limits of the cellules, and extending the entire length of the 

 Btipe, there is a longitudinal depressed line ; and along this line; and run- 

 ning thence almost rectangularly to the outer limits of the stipe just above 

 the aperture, the cell-partitions join the exterior test, and project in an 

 extended border or flange. 



In specimens stripped of the test, where the interior has been filled with 

 stony matter, the cell-partitions present the appearance shown in fig. 3, 

 plate ii ; while there is a large central space apparently occupied bjr the 

 common body, but without the appearance of a central axis on the exterior 

 surface. When the surface is ground down to a plane intermediate between 

 the exterior and the centre, it presents the aspect of fig. 4 ; and when the 

 cutting is carried to the centre, it gives the characters of fig. 5, the cell- 

 divisions apparently reaching to the axis. 



. The general form of this stipe in section (fig. 6) approaches that of 

 Retiolites, as shown by Barrande and Geinitz ; and in the arrangement 

 of the common body and axis, there is a departure from the typical diprio- 

 nidian forms of Graytolithus. In this transverse section we have a some- 

 what concavo-convex form, which is narrower on the concave side. There 

 is a central or sub-central point indicating the filiform solid axis ; -and on 

 each side of this are the divisional cell-walls, which produce a slight con- 

 traction of the exterior walls of the stipe at the inner limit of their 

 attachment. Another section, fig. 7, shows the same features, together 

 with the remains of two other cell-divisions, neither of which reach to the 

 exterior walls of the graptolite ; and the one on the right hand shows the 

 narrow extremity just before joining the axis. 



These sectiops, together with numerous other longitudinal, transverse 

 and oblique sections, compel us to conclude that this graptolite possesses a 

 a filiform central or sub-central apparently solid axis ; and that the cell- 

 partitions originate from, or are joined to this axis. These cell-partitions 

 appear to consist of triangular plates, which have an unequally arching or 

 convex upper surface, and a concave lower surface. This form of cell- 

 partitions would leave the alveoles to communicate at their bases with the 

 common body on each side.* 



* The cell partitions in this form of graptolites are represented as they appear to exist 

 in the solid specimens examined, on Plate ii, fig. 9 ; where, curving gently downwards 



