EXPLANATION OF THE PLATES. 7 
This Lingula has not yet been identified with certainty in Ireland, al- 
though specimens collected some time since by the Geological Survey at Bel- 
lewstown, near Duleek, county of Meath, were doubtfully referred by the 
author to this species. With regard to these specimens, Mr. Davidson, to 
whom they were submitted, makes the following remarks :—‘ In the Lower 
Silurian shales of Bellewstown, county of Meath, Ireland, we find some 
flattened, distorted Lingulee, which may perhaps belong to Davisii. We 
have given a figure of them in our plate.’ a Sil. Brach. Pal. Soc., 
p. 58, pl. iv., fig. 12. 
Fic. 4.—a, b. ORTHIS LENTICULARIS, Dalman. 
J. W. Salter in Memoirs Geological Survey, vol. iii., p. 339, pl. iv., figs. 
a. 
b. 
8-10. 
From Memoirs Geological Survey, vol. iii., pl. iv., fig. 9a. A portion 
of rock, with several examples of this small species of Orthis, the earliest 
known in British rocks. 
Enlarged figures of the same species, from Memoirs Geological Survey, 
vol. ini., pl. iy.,, fig; 9): 
Upper LInGuna FLAGS. —Penmorfa Church, Tremadoc; near Criccieth, at 
Ogof-ddu Cliffs, North Wales. Memoirs Geological Survey, vol. iii., p. 340. 
