ll
the Revolution, and has since been restored. The bishops received the
title of count from the emperor Henry I. (919-936), and in 1510 were
raised to the dignity of dukes, their territory including the town
itself and its territory, called Cambresis.

See E. Bouly, _Histoire de Cambrai et du Cambresis_ (Cambria, 1843).

CAMBRIA, the Med. Lat. name for Wales. After the end of the western
Roman empire the Cymric Celts held for a while both Wales and the land
round the Solway (now Cumberland and adjacent regions), and the former
came to be called Cambria, the latter Cumbria, though the two names were
sometimes interchanged by early medieval writers.

CAMBRIAN SYSTEM, in geology, the name now universally employed to
designate the earliest group of Palaeozoic rocks which possesses a
connected suite of fossils. The strata of this system rest upon the
Pre-Cambrian, and are succeeded by the Ordovician system. Until the
fourth decade of the 19th century all stratified rocks older than the
Carboniferous had been grouped by geologists into a huge and indefinite
"Transition Series." In 1831 Adam Sedgwick and Sir Roderick I. Murchison
began the herculean task of studying and sub-dividing this series of
rocks as it occurs in Wales and the bordering counties of England.
Sedgwick attacked the problem in the Snowdon district, where the rocks
are highly altered and displaced and where fossils are comparatively
difficult to obtain; Murchison, on the other hand, began to work at the
upper end of the series where the stratigraphy is simple and the fossils
are abundant. Murchison naturally made the most of the fossils
collected, and was soon able to show that the transition series could be
recognized by them, just as younger formations had fossils peculiar to
themselves; as he zealously worked on he followed the fossiliferous
rocks further afield and continually lower in the series. This
fossil-bearing set of strata he first styled the "fossiliferous
greywacke series," changing it in 1835 to "Silurian system."

In the same year Sedgwick introduced the name "Cambrian series" for the
older and lower members. Murchison published his Silurian system in
1839, wherein he recognized the Cambrian to include the barren slates
and grits of Harlech, Llanberis and the Long Mynd. So far, the two
workers had been in agreement; but in his presidential address to the
Geological Society of London in 1842 Murchison stated his opinion that