336 BRITISH GRAPTOTJTES. 



Sub-genus Gladiograptus, HopJdnson and Lapworth. 



1850. Gladiolites, Barrande, G-rapt. de Boheme, p. 68. 



1875. Gladiograptus, Hopkinson and Lapworth, Quart. Journ. Geol. Soc, vol. xxxi, p. 659. 



The name Gladiograptus was first suggested by Hopkinson and Lapworth 

 (lor. cit. supra) as a synonym for Barrande's original name Gladiolites used by him 

 in the diagnosis of his Betiolites Geinitzianus; and it is here restricted to those 

 forms typified by that species. The sub-genus includes two British species 

 and two varieties. 



Retiolites (Gladiograptus) Geinitzianus, Barrande. Plate XXXIV, figs. 8 a — d. 



1850. (Gladiolites) Betiolites Geinitzianus, Barrande, G-rapt. de Boheme, p. 69, pi. iv, figs. 16 — 33. 



1851. Betiolites Geinitzianus, Suess, Ueber Bohmische Grapt., p. 95, pi. vii, figs. 1 d — e. 



1852. Betiolites Geinitzianus, Geinitz, Die Grapt oliten, p. 52, pi. vi, figs. 1 — 8. 



1868. Betiolites Geinitzianus, Nicholson, Quart. Journ. Geol. Soc, vol. xxiv, p. 530, pi. xix, figs. 19, 20. 

 1882. Betiolites Geinitzianus, Tullberg, Skanes Grapt., p. 41, pi. i, figs. 10 — 17. 

 1890. Betiolites Geinitzianus, Holm, Gotlauds Grapt., Bihang. till k. Svensk. Vetensk.-Akad. Handl., 

 vol. xvi, pt. 4, no. 7, p. 18, pi. ii, figs. 2 — 5. 



Polypary sword-shape, robust, truncato- elliptical in transverse section, becoming 



concavo-convex as growth proceeds ; 3 — 5 cm. or more in length, and 



widening steadily from a rounded base to a maximum breadth of 5 mm. 



Thecse distinct, fourteen to nine in 10 mm., in contact throughout; outer 



walls finely reticulate, roof and floor membranous and continuous. Apertural 



margins normal, quadrangular, destitute of ornament. Clathria well 



developed, best shown in compressed specimens, the straight and zigzag 



strands being usually conspicuous, especially the former. Eeticula fully 



developed, with sub-regular, rounded, or polygonal meshes. 



Description. — The polypary in this species is sword-like in shape, and from 



specimens preserved in relief appears to have been truncato-elliptical in transverse 



section at the proximal extremit}^ becoming more concavo-convex distally, the 



central portion of the concave aspect being somewhat raised above the general 



level (Barrande). 



The sicula has not been observed with certainty in British examples. 

 The thecas are in contact throughout, and are, as a rule, mutually compressed 

 into the form of hollow prisms, almost square in section, and from three to four 

 times as long as wide. 



The apertural margins are practically normal to the axis of the theca, but in 

 compressed specimens have the appearance of being inclined. They vary in 



