LICHAS ANGLICUS. 95 



Pygidium large, semicircular, with slightly arched anterior margin. Axis 

 narrow, convex, cylindrical, and short, being only half the length of the pygidium 

 or even less, composed of 5 — 7 narrow weak rings and a terminal pointed piece 

 about one third the total length of the axis. Width of axis equal to about one 

 seventh that of the pygidium. Lateral lobes weakly convex, with concave, 

 depressed border, not sharply defined. Lateral lobes composed of six pairs of 

 narrow rounded indistinct pleime radiating from the sides of the axis, and of a 

 wide posterior smooth portion traversed down its centre by a single median 

 narrow rib extending straight back from the extremity of the axis. All the ribs 

 die out gradually towards the margin, and do not cross the concave border. 



Remarks. — This species was first described by Nicholson and Etheridge ("7'. 

 cit.), but the acquisition of further and better material has enabled me to give a 

 fuller and amended diagnosis. This species may be considered as a near ally of 

 Ogygia ? concentrica, Linnarsson, 1 from the Beyrichia Limestone of Sweden. The 

 relations of the genus have been discussed by Nicholson and Etheridge (op. cit.), 

 and I am in agreement with their conclusions, which need not be here repeated. 



Collections. — Mrs. Gray (f. M.) ; Museum of Practical Geology ; Edinburgh 

 Museum. 



Horizon and Localities. — Balclatchie Group (Llandeilo) : Balclatchie ; Ardmillan. 

 P Stinchar Limestone Group (Llandeilo) : Aldons. 



Family Liciiadj i>.k. 

 Genus LICHAS, Dalman. 

 1. Lichas (Corydocephalus) anglicus (Beyrich), 184(3. 



P 1840. Peltura buchlandi, Milue Edwards, Hist. Foss. Crust., vol. iii, p. 345, pi. xxxiv, fig. 12. 



1846. Arges anglicus, Beyrich, Untersuch. tib. Trilob., pt. ii, p. 6, pi. i, fig. 3. 



1850. Lichas bucldandi, Fletcher (e.p.), Quart. Journ. Geol. Soc, vol. vi, p. 235, pi. xxvii, figs. 2, 3, 



4, ? 5, 5a (non figs. 1, la) ; pi. xxvii bis, figs. 1, la, U. 



1854. Acanthopyge anglica, M'Coy, Syuops. Brit. Pal. Foss. Woodvv. Mus., p. 151. 



— Lichas anglicus, Morris, Cat. Brit. Foss., 2nd ed., p. 110. 



1859. Lichas anglicus, Murchisou, Siluria, 2nd ed., Foss. 63, fig. 1. 



1867. Lichas anglicus, Murchisou, ibid., 4th ed., p. 234, Foss. 64, fig. 1. 



1873. Lichas anglicus, Salter, Cat. Camb. Silur. Foss. Woodw. Mus., p. 130. 



1877. Lichas anglicus, Woodward, Cat. Brit. Foss. Crust., p. 42. 



1902. Lichas (Corydocephalus) anglicus, Reed, Quart. Jouru. Geol. Soc, vol. lviii, p. 71. 



1903. Lichas (Corydocephalus) anglicus, Reed, Geol. Mag. [4], vol. x, p. 3, pi. i, figs. 1, 2 (varieties). 



1 Liunarsson, ' Vestergotl. Camb. Silur. Aflagr.' (1869), p. 75, pi. ii, figs. 37—40. 



