148 THE SEQUENCE OF THE CAMBRIAN [Feb. 1902, 
Discusston. 
Prof. LaewortH spoke of the excellent work done by the Author 
in unravelling the complicated geology of the Malvern Hills, and 
congratulated him and the Society upon the interest and importance 
of the present communication. 
With regard to the Hollybush Quartzite, it seemed desirable that 
some alternative name should be suggested for the sake of distinc- 
tion. He agreed with the Author in his reference of the Hollybush 
Group as a whole (including the Quartzite) to the general geological 
period embracing the so-called Etcheminian, the Olenellus-zone, and 
the Paradoxidian. We ought, however, carefully to bear in mind 
that as yet the Olenellus-zones marked by forms similar to Olenellus 
Thompsont and those marked by forms of the type of Holmia 
(Olenellus) Kjerulfi have not yet been demonstrated to be con- 
temporaneous ; and also that the Etcheminian fauna, claimed as 
pre-Cambrian by some, is as strenuously claimed as Cambrian by 
others. It is certainly safest in the meantime to refer all these 
pre-Paradoxidian fossil-bearing beds to the Lower Cambrian, 
It is not unlikely, as the Author has suggested, that the higher 
parts of the Malvern Hollybush Sandstone Series answer to the 
much thinner and less arenaceous beds of the Purley Shales of 
Nuneaton. This correlation would harmonize with the known 
thinning of the Cambrians when followed eastward into Europe, 
and also with their thickening and the coming-in of more arenaceous 
deposits when followed in the contrary direction, as for example 
into the Harlech district, where Dr. Stacey Wilson and himself, in 
mapping that country, had found that the Lower Cambrians were 
represented by several massive arenaceous formations separated by 
shaly zones. 
As respects the carrying downward of the systematic base of the 
Ordovician System from the bottom of the Upper Tremadoc (Lower 
Arenig of Hicks), where it was originally drawn, to the bottom of 
the Lower Tremadocas proposed by the Scandinavian geologists, there 
could be no question that, as the term ‘ Ordovician’ was suggested 
as a title for the rock-formations containing the second Lower 
Paleozoic fauna, the geological horizon which most naturally and 
conveniently divided the first from the second fauna must, in the 
nature of things, be the base-line of the Ordovician System. The 
credit of showing that such was the most natural line of division 
between the Cambrian and the Ordovician in Europe belonged solely 
to Linuarsson and Brogger. Linnarsson selected this line as the base 
of the Scandinavian Ordovician many years ago; and Prof. Brégger, 
in his recent brilliant paper on the ‘ Huloma-Niobe Fauna,’ has 
shown that it appears to be the most natural basement-line all 
over the world. Moberg’s further proposal to include also the 
Scandinavian Dictyonema-flabelliforme zone in the Ordovician is 
quite justifiable, and has been already adopted by some. But to 
what extent the Dictyonema-zones of other regions answer to the 
Dictyonema-zone of the Baltic basin, we have yet to discover; and 
