EXPLANATION OF THE PLATES. 35 
PLATE XII. 
FOSSILS OF THE CARADOC OR BALA ROCKS. 
MOLLUSCA.—BRACHIOPODA. 
Fic. 1.—a, 6. SrROPHOMENA EXPANSA, Sowerby, sp. 
Orthis expansa, Sil. Syst., p. 638, and O. pecten, ibid. (Strophomena, Cat. 
Brit. Foss., 1854, p. 137). Sil., fourth edition, pl. vi., fig. 4. 
a. Original. Exterior of ventral valve, showing the strong radiating and 
intermediate fine striz. 
b. Original. Internal impression of fig. 1 a; both in fine-grained greenish 
sandstone, from Cheney-Longville, Shropshire. Mus. G. S. I. 
Carapoc.—Sil., fourth edition, p. 528. Abundant in Shropshire and North 
Wales; also in Ireland at the following places in Caradoc rocks: Tramore 
Bay, Co. Waterford ; Portraine, and Lambay Island, Co. Dublin; Grange- 
geeth, Co. Meath; and Desertcreat, Co, Tyrone. Mus. G. 8. I. 
CONCHIFERA. 
Fic. 2.—Mopio.orsis EXPANSA, Portlock, sp. 
Modiola, Geol. Rep. Londonderry, &e., p. 425. Modvolopsis, Sil., fourth 
edition, p. 530. 
Original. In dark grey micaceous schist, Desertcreat, Tyrone (Portlock 
Collection). Mus. G. 8S. I. 
Carapoc.—Co. Tyrone. 
Fig. 3.—Mopi0.orpsis oBtiqua, Sowerby, sp. 
Avicula, Sil. Syst., p. 635. Modiolopsis, Sil., fourth edition, pl. vii., fig. 2. 
From Sil. Syst., pl. xx., fig. 4. Internal cast in Caradoc sandstone, Soud- 
ley. 
Gi ped. This species occurs in clusters in the Caradoc sandstone, at 
Soudley, near Acton Scott; east flank of Caer Caradoc, Sil. Syst., p. 638. 
It is also included in the list of Caradoc fossils from North Wales, at 
Bettws-y-coed, Caernarvonshire, and east of Bala Lake, Merionethshire. 
M. G.S,, vol. iii., p. 270. 
Fig. 4.—a, b. CreNoponta oBLiqvua, Portlock, sp. 
Arca obliqua and cylindrica. Geol. Rep. Londonderry, pp. 428-9. 
Ctenodonta obliqua, Sil., fourth edition, p. 529. 
a. Original. Indark grey micaceous schist, Desertcreat, Tyrone. Mus. G. 
wD. 
