22 EXPLANATION OF THE PLATES. 
Bellerophon perturbatus, Siluria, third edition, p. 218; Foss. 39, fig. 6, and 
pl. x., fig. 5. Mem. Geol. Surv., vol., 1ii., p. 350, woodcut, fig. 16. 
a. From the original figure in Silurian System, pl. xxii., fig. 15. 
b. From the woodcut in Mem. Geol. Surv., vol. iii, fig. 16, p: 350. ‘“ One of 
the very best and most characteristic species for the Llandeilo Flags, being 
common in British localities in North and South Wales, and very rarely 
met with (in Ireland only) in rocks, supposed to be of the Caradoc era.” 
Mr. Salter, in Appendix to Mem. Geol. Surv., vol. ili., p. 350. 
The author has identified this species from cleaved slates, supposed to 
be of Caradoc or Bala age, at Slieveroe, near Rathdrum, Co. Wicklow ; 
and it occurs plentifully in the collections of fossils made by the Geologi- 
cal Survey of Ireland, at Newtown Head, Waterford Harbour. 
Upper LuanprrLo.—Bath House, Bangor; abundant in Upper Llandeilo 
Rocks in North and South Wales; and in Caradoc P S. E. Ireland. Loca- 
lity mentioned in Catalogue of British Fossils, by Prof. Morris, under the 
name of Huomphalus perturbatus. Pensarn, Caermarthen. 
PTEROPODA. 
Fig. 138. Macturea Loaant, Salter. 
Journ. Geol. Soc., vol. vii., pl. viii., fig. 7. Siluria, third edition, p. 215; 
Foss. 37, fig. 1. Geological Survey of Canada, Dec. 1, pl. i., fig. 6. 
From Journ. Geol. Soe. (above cited), pl. viii., fig. 7 b, reduced to half natural 
size. 
LuanpEiLo.—In Limestone, Aldeans, Ayrshire. 
Fic. 14.—a, 6. Macturta Praca, Salter. 
Journ. Geol. Soc., vol. xv., pl. xiii, figs. 4,5; Siluria, third edition, p. 217; 
Foss. 38, figs. 1, 2. 
a, b. Reduced figures of the operculum, or plate for closing the mouth of the 
shell; from Journ. Geol. Soc., above cited. a, inner view ; 5, exterior. 
LLANDEILO.—Limestone, Durness, Sutherlandshire. 
Fig. 15.—TuHerca simpiex, Salter. 
Siluria, third edition, p. 50; Foss. 8, fig. 5. 
From Mem. Geol. Surv., vol. iii., p. 352, pl. xi. B, fig. 24. The pointed end 
being restored in outline. 
Lower LLANDEILO.— White Grit Mine, Shelve, Shropshire ; abundant. 
CEPHALOPODA. 
Fie. 16.—OrtHocERAS AVELINU, Salter. 
Siluria, third edition, p. 50; Foss. 8, fig. 4. 
From Mem. Geol. Surv., vol. iii., p. 356, pl. xi. B, fig. 18. 
LoweErR LiuaANDEILO.—Cefn Gwynlle Mine, Shelve, Shropshire. 
