28 British Association Reports. 



and remote period, in which, very few, even of the genera of fossil 

 animals common in the great Silurian deposits are to be found ! All 

 is distinct and anterior, the genera lower in point of organization, 

 the species more limited in number, and, even, with some remarkable 

 exceptions, diminish in size. We seem to be coming towards the 

 zero of animal if not of vegetable life. 



With regard to the distribution of the fossils themselves. The 

 lowest beds, which actually lie among the uppermost coarse beds 

 of the Cambrian grits ! (only distinguished from them by the want 

 of purple colour,) contain a species of Paradoxides (P. aurora), with 

 which are associated some minute Trilobites, Agnostus. Microdiscus, 

 etc. Further up we have Paradoxides again, but of a distinct 

 species, and larger size — P. Hicksii. The mass of the fossils then 

 come in (in all thirty-five species are known), Crustacea, shells, and 

 sponges ; and higher up in the series a third Paradoxides, so large as 

 to have attracted general notice — the well-known P. Davidis. The 

 genus is unknown in this country above the horizon of this old 

 formation, Olenus taking its place in the Ffestiniog group. 



As indicative of the value of a close observation of these old 

 faunas, it may be sufdcient to say, that by means of this Mensevian 

 groiip we can ascertain the true horizon of the gold-bearing rocks 

 of Wales ; we can also identify more accurately the oldest fossil- 

 bearing strata of Bohemia and Sweden with those of our own 

 country ; and assign them an exact position, with respect to British 

 strata, in the older Palseozoic series. 



The genus Paradoxides becomes in this way one of the medals of 

 creation, and the index of a most remote age — so remote, that only 

 a few, and those the humbler members of the invertebrate classes, 

 inhabited the sea — before the cuttlefish or even the nautilus was 

 created ; as these last were long anterior to the very earliest of 

 the fishes. 



Mr. Hicks described beds of contemporaneous trap, such as had 

 been previously noticed by his colleague, as abundant in the lower 

 strata of the group. He also showed their origin and direction. 

 The faults of the region, chiefly N.W. ones, were touched upon, 

 but could not be fully described. The district is evidently a pro- 

 lific one, containing a new and most interesting formation ; and as 

 St. David's Cathedral is now being restored, and as there are ex- 

 cellent bathing places close by, it is likely that this remote corner 

 of the island will attract both geologists and non-scientific visitors. 



The paper having been read, the natural history of the new 

 formation was treated in a condensed form by Mr. Salter, who 

 called attention to the fact that no less than three distinct fossil-bear- 

 ing formations — the Tremadoc, Ffestiniog, and Menasvian groups — 

 were now traceable below the Llandeilo Flags proper and the 

 " Arenig and Skiddaw group," which last, the "Lower Llandeilo" 

 of Murchison, and the equivalent of the " Quebec group " of Canada, 

 forms the natural base of the Lower Silurian series. 



The time allotted to the authors was but short, and only the 

 general facts of the communication could be touched upon. 



