LICHAS. CYPHASPIS. 17 



Hall, 1 the frontal lobe is much larger compared with the size of the head, and has 

 more arched sides, and the cheeks are very small ; and in L. Bigsbyi* which is a 

 much more conical form, the frontal lobe is wider and more globose. In the 

 British Silurian L. anglicus, Beyr., and L. Salteri, Fletcher, 3 the frontal lobe is of 

 a less rectangular shape, and the arrangement of the cheek in regard to the neck- 

 lobe is different. 



V. Family. — Peoetid^, Barrande. 

 1. Genus. — Cyphaspis, Burmeister, 1843. 



This genus is defined by its tumid and deeply furrowed head, its small and 

 elevated almond-shaped eyes, its numerous body-rings, and its long aciculate 

 spines. It occurs in the Silurian and Devonian. G. ceratophthalma which 

 Goldfuss described under his genus Gerastus is the type species. 



1. Cyphaspis ocellata, Whidborne. PI. I, figs. 20 — 22, and PI. II, fig. 18. 



1889. Cyphaspis ocellata, Whidb. Geol. Mag., dec. 3, vol. vi, p. 29. 



Description. — Body small and tumid. Cephalic shield wide, very convex, deeply 

 grooved. Border prominent, elevated, bearing irregular tubercles ; in outline 

 slightly convex in front, curving rapidly round the free cheeks, coming straight to 

 the angle, and thence continued in a long, straight, or sabre-shaped spine ; in 

 elevation, high in the rostral part, and sweeping down rapidly till its horizontal 

 direction has changed. Glabella small, extremely prominent, egg-shaped, raised 

 much above the rest of the head, without furrows, covered with fine, sharp- 

 headed tubercles. Neck-furrows broad, enclosing a small lateral lobe or 

 tubercle. Neck-lobe lower than the glabella, broad, short, flattened, much 

 arched. Lateral processes of the neck concave toward the cheek. A wide tumid 

 area between the frontal lobe and the border extending round and swelling out to 

 form the cheek, on the summit of which is placed the eye, which is smooth and 

 globular, and rises on a kind of stalk almost as high as the glabella, and rather 

 near to it, but sloping outwards. Surface of cheek marked with a few large nodules 

 round the base of the eye, and on the rest of it a few others interspersed with 

 small granules and ridges (and pits), the two latter predominating in the groove 

 before the border. 



1 1888, Hall, ' Pal. N. Y.,' vol. vii, p. 81, pi. xixB, figs. 1, 2, and pi. xxv, fig. 5. 



2 1859, Ibid., vol. iii, p. 364, pi. lxxvii, figs. 1—8, and pi. lxxviii, figs. 5, 6. 



3 1852, Fletcher, ' Quart. Journ. Geol. Soc.,' vol. vi, p. 257, pi. xxvii, fig. 9, and pi. xxvii bis, 

 fio;. 4. 



