250 Mr. C. Lap worth on the Geological 
Caradoc or later age, and are distinctly mapped by Jukes, on 
physical grounds, as lying far up in the Caradoc series * * * § . 
Similar strata interbedded with the highly fossiliferous lime¬ 
stones of Amlwch in Anglesey are regarded as Llandeilo for 
a corresponding reason, in distinct opposition to the circum¬ 
stance that the limestones yield typical Caradoc formsf. The 
black shales, traps, limestones, and grey flags that form por¬ 
tions of the counties of Waterford and Wexford, in the S.W. 
corner of Ireland, afford us another instance of the same phe¬ 
nomenon. These strata, much contorted, are well seen upon 
the shores of the triple estuary of the Suir, Nore, and Barrow, 
where they are, in places, abundantly fossiliferous, the calca¬ 
reous beds swarming with well-known Caradoc Testacea and 
Crustacea, and the interbedded dark shales yielding numerous 
and well-preserved Graptolites. Murchison himself is said 
to have expressed the opinion that, while the calcareous beds 
ought to be assigned to the Caradoc, there could be no doubt 
that the fauna of the associated black shales was as distinctly 
Llandeilo. Jukes, from personal knowledge of the rocks, 
on the other hand, confidently asserted that the so-called 
Llandeilo forms were intimately associated physically with 
the beds so rich in Bala fossils, and could not be separated 
from the rest of the series {. He admitted, however, without 
demur the correctness of the reference of the fauna of the 
graptolitiferous beds to the Llandeilo formation, eluding the 
difficulty by expressing his opinion that u the occurrence of 
small assemblages of Llandeilo species here and elsewhere in 
Ireland in peculiar beds, which are, as far as can be deter¬ 
mined, interstratified with the beds containing Bala or Cara¬ 
doc species, reminds us of Barrande’s colonies. He had long 
suspected that the two assemblages of species were contempo¬ 
raneous in reality, and had each their peculiar habitat, their 
occurrence as fossils depending on the nature of the rock, quite 
as much as its period of formation” §. Mr. Bailyll, a few 
years later, cited this opinion in support of his own more 
correct view that similar dark shales in Central Ireland were 
actually of true Caradoc-Bala age—a view he finds himself 
compelled to adopt in this instance, as they were clearly inter¬ 
stratified with beds affording typical Caradoc-Bala fossils. 
* Ramsay, 1 Geology of North Wales,’ pp. 107, 259. 
t Ibid. pp. 189, 258 
| Jukes, Mem. Geol. Surv. Ireland, Explan. Sheet 167, p. 28. 
§ Ibid. p. 30. 
|| Raily, Mem. Geol. Surv. Ireland, Sheets 81, 82, pp. 13,14 j Sheet 49, 
p. 18. 
