11 
and that every one of those fossil forms was once endowed with the gift of 
life. Then again that straight Nautilus, the Orthoceras, represents, as far as we 
know, the highest form of living animal the Llandeilo seasnourished. No remains 
of any fish or other vertebrate animal have ever been found throughout all the 
length and breadth of the Lower Silurian strata wherever they have been searched, 
and Sir Roderick Murchison called the Orthoceratites ‘‘ the scavengers of the seas,” 
and considered that they occupied in those times the place which in after epochs 
was to be filled by the predaceous fishes. And such, indeed, appears to be the 
teaching of the rocks! All geologic evidence now tends to prove that the simpler 
forms of life were the first forms called into existence. Trilobites, Orthoceratites, 
and other mollusca preceded the fish, the fish preceded the reptile, the reptile the 
bird, the bird the mammalian quadruped, and the mammalian preceded man. 
The Caradoc or Bala strata, which overlie the Upper Llandeilo rocks west 
of Llandovery and Llandeilo, are not found in the Builth district. They were 
probably denuded here, for the May-hill rocks (or Upper Llandovery deposits) 
are found full of Pentameri and other characteristic fossils resting unconformably 
upon the upheaved Llandeilo strata, and there interbedded with lavas and volcanic 
ash. In order to see these strata the explorer must go westwards and explore the 
hill country around the Drygarn mountain and near Llandeilo and Haverfordwest. 
They appear also on the banks of the Wye, near Newbridge, where the Tarannon 
shales rest unconformably upon them. 
In walking from Builth by the beautiful grounds of Welfield with its 
Llandeilo Trilobites Ogygia, Asaphus, Ampyx, and Agnostus, and its lingulas and 
orthides among its {shells, you arrive at Pencerrig, another property of the family 
of Thomas, and here you find igneous rocks both eruptive and stratified with 
Llandeilo flags, while on and against them rest the May-hill beds (Upper 
Llandovery rocks) full of fossils, and which constitute the base of the Upper 
Silurians. These beds may be seen at the upper end of Pencerrig Lake. 
Welfield and Pencerrig are classic ground to the geologist, for here among the 
groves and hills and quarries have been the haunts of Buckland and Conybeare, 
Murchison, and Sedgwick, who in former years were attracted by the rich 
profusion of Trilobites in the shales and the beauty of the surrounding scenery. 
Mr. Symonps hoped and trusted that the owners of these houses would 
gather around them, if indeed they did not already possess them, some of the 
beautiful specimens which geologists of the past had travelled hundreds of miles to 
see, and he might predict the same of the geologists of the future. 
The Upper Silurians of the Builth district take us into beautiful scenery, 
for there is Aberedw, often the home of Llewelyn, and its picturesque glen, and in 
the rocks there I have found Pentamerus Knightii, that noble Upper Silurian shell 
which is so abundant in the Aymestry limestone of Aymestry and the Ludlow 
country. Near Llanstephan, too, there are at Pwll-ddt beautiful rocks clothed 
with foliage which furnish many an Upper Silurian fossil, and the Calymene 
Blumenbachii and other Trilobites may be found below the waterfall of the Black 
Rock. Here, too, we have an example, on a limited scale, how the hardness of 
