15 
Bellerophon perturbatus ... 4 specimens Llandeilo species. 
Calymene Blumenbachii 
I 5 
do. 
Llandeilo chiefly. 
variety brevicapitata 
i 
Ampyx mammilatus (Sars) 
} 2 
do. 
Llandeilo elsewhere, 
■ Austinii (Portlock) 
Trinucleus seticornis... 
... 3 
do. 
Caradoc usually. 
Ogygia Portlockii (Salter) 
... 3 
do. 
Most like Llandeilo. 
Acidaspis Jamesii 
... 1 
do. 
Peculiar to deposit. 
Salteria ... 
... 1 
do. 
The remarks opposite the names are not mine, but were appended at the 
Museum of Practical Geology; and the following letter accompanied the 
list of fossils. 
" M. P. Geology, Jermyn Street, Feb. 28, 1862. 
Dear Sir, — The list I enclose will show how interesting these Llandeilo 
localities are. You are quite right. But if any one chose to call them 
Caradoc he would be justified, for there is a mixture of Llandeilo and 
Caradoc types which I did not expect. I rather think they are both of the 
same age, and that Calymene duplioata, and the Ogygia settle the matter of 
their age sufficiently. Beds of passage between two such closely related 
formations could not but be looked for. — Here they are. 
I have retained specimen 33, as it seems to have a new form in it which 
I believe my friend Dr. Thomson has called Salteria. Please let me keep it 
a month ; it shall be returned safely. Yours truly, 
J. W. Salter." 
Prom Mr. Salter's letter it will be seen that the Duncannon beds are 
admitted to be true Llandeilo Flags, and that he was also inclined to go 
further than I had proposed and include the fossiliferous beds at Newtown 
Head on the Waterford side of the estuary in the Llandeilo series. I was 
not, and am not now inclined to agree wholly with this view, for although 
Llandeilo fossils are found mingled with true Caradoc species, yet I cannot 
consider that we are justified in regarding the Newtown Head, Woodstown, 
strata as anything more than the passage beds between the two formations, 
and that during the deposition of the less ancient beds the fauna of the 
Llandeilo period had not wholly died out, but continued to exist for some 
time along with true Caradoc types. 
The same mixture of Llandeilo and Caradoc fossils has been noticed by 
Mr. Randall at Cound Brook, a tributary of the Severn, in strata which 
have always been considered as of undoubted Caradoc age. 
