334 PROCEEDINGS OF THE 



G. laxa. This species we only know from the Hairmyres shale, 

 where it is somewhat rare. It is found in fragments of fronds, 

 rarely exceeding 1 J inches in length, which show very distinctly the 

 bipinnate mode of branching at wide intervals. 



Explanation of Plates. 



All the Figures loere draton ivith the Camera lucida, from specimens in the 



Cabinet of Mr J. Young, F.G.S. 



Plate II. 



Figs. 1-7. — Glauconome flexicarinata, nobis. 



Fig. 1 shows ridge on stem distinct from that forming lip of cell on branch. 

 Figs. 2 and 6 show irregularity in number of ridges which in figs. 6 and 4 are 

 reduced to isolated tubercles. In fig. 5 the ridges of stem are not continuous 

 with those on branch. In fig. 4 the branching is neaiij^ bifurcate. Fig. 3 

 (drawn upside down) shows this, as seen on the polished face of a vertical section 

 through the middle line of stem and branches! Fig. 7 shows ornament of non- 

 celluliferous face. 



Figs. 8-10. — G. retrojlexa, nobis. 



Fig. 8 — Front view of somewhat worn specimen. Fig. 10 — Ti-ansverse 

 horizontal section showing backward flexure. Fig. 9 — Polished section in 

 middle plane of stem. 



Plate III. 



Figs. 11-13. — G. retrojlexa, nobis. 



Fig. 11 — Unworn specimen, showing granulation of obverse. Fig. 12 shows 

 the striation and tubercles of reverse of same specimen. Fig. 13 illustrates 

 irregularity of ornament of reverse. 



Figs. 14-21. — G. {Diplopora) marginalis, nobis. 



Figs. 14 and 15 show the pyriform apertures due to the abrasion of the 

 septum between the two orifices (figs. 17 and 21). Fig. 16 shows irregularity 

 of the secondary ridges, which are obsolete in figs. 15 and 18. Fig. 19 shows 

 the reverse face with its ornament, which is enlarged in fig. 20. 



Figs. 22-24. — G. aspera, nobis. 



Fig. 22 shows the habit of the species, natural size. Fig. 23 illustrates the 

 character of the ornament and the twist of the stem. Fig. 24 shows the 

 tuberculate striate ornament of the reverse. 



Plate IV. 



Figs. 25, 26. — G. steUipora, nobis. 

 Figs. 25, 26. — Obverse faces of different specimens. 



Figs. 27-32. — G. clegans, nobis. 

 Fig. 27 is from a slightly worn specimen. Fig. 28 shows more distinctly the 

 prominence of the upper margin of the cell aperture. Fig. 29 is an enlarge- 



