566 Notices of Memoirs — 



second group embraces the Levant, Surgent, Scalent, and Pre-Meridional. These are 

 said to be " the very near representatives of the true European Silurian, regarding 

 this series as commencing with the May-Hill sandstone." The Levant division is 

 farther declared to be the equivalent of the sandstone just named; while the 

 Matinal is made to correspond to the Landeilo, Bala, or Upper Cambrian ; the 

 Auroral with the Ffestiniog or Middle Cambrian ; and the Primal with the Lingula- 

 flags, the Obolus sandstone of Russia, and the Primordial of Bohemia. 



The range of Silurian should therefore be restricted, as maintained by Sedgwick 

 and by the Messrs. Rogers, to the rocks of the third fauna : the so-called Upper 

 Silurian of Murchison ; and the names of Middle Silurian, Lower Silurian, and 

 Primordial Silurian banished from our nomenclature. The Cambrian of Sedgwick, 

 however, includes the rocks both of the first and second faunas. To the former of 

 these, the lower and middle divisions of the Cambrian (the Bangor and Ffestiniog 

 groups of Sedgwick), Phillips, Lyell, Davidson, Llarkness, Hicks, and other 

 British geologists, agree in applying the name of Cambrian. The great Bala 

 group of Sedgwick, which constitutes his Upper Cambrian, is, however, as 

 distinct from the last as it is from the overlying Silurian, and deserves a not less 

 distinctive name than these two. Its original designation of Upper Cambrian, 

 given when the zoological importance of Lower and Middle Cambrian was as yet 

 unknown, is not sufficiently characteristic ; and the same is to be said of the name 

 of Lower Silurian, wrongly imposed upon it. The importance of this great Bala 

 group in Britain, and of its North American equivalent, the Matinal of Rogers, — 

 including the whole of the limestones of the Trenton group, with the succeeding 

 Utica and Hudson-River shales, — might justify the invention of a new and special 

 name. That of Cambro-Silurian, at one time proposed by Sedgwick himself, and 

 adopted by Phillips and by Jukes, was subsequently withdrawn by him, when 

 investigations made it clear that this group had been wrongly united with the 

 Silurian by Murchison. Deference to Sedgwick should therefore prevent us from 

 restoring this name, which, moreover, from its composition, connects the group 

 rather v/ith the Silurian than the Cambrian. Neither of these objections can be urged 

 against the similarly-constructed term of Siluro-Cambrian, which moreover has the 

 advantage that no other new name could possess, of connecting the group both with 

 the true Silurian, to which it has very generally been united, and with the 

 Cambrian, of which, from the first, it has formed a part. I therefore venture to 

 suggest the name of Siluro-Cambrian, as a convenient synonym for the Upper 

 Cambrian of Sedgwick (the Lower Silurian of Murchison), corresponding to the 

 second fauna ; reserving at the same time the name of Cambrian for the rocks of 

 the first fauna, — the Lower and Middle Cambrian of Sedgwick, — and restricting 

 v/ith him the name of Silurian to the rocks of the third fauna, — the Upper Silurian 

 of Murchison. 



It would be unjust to conclude this historical sketch of the names Cambrian and 

 Silurian in Geology, without a passing tribute to the venerable Sedgwick. The 

 labours of his successors in the study of British geology, up to the present time, 

 have only sei-ved to confirm the exactitude of his early stratigraphical determin- 

 ations ; and the last results of investigations on both continents unite in showing 

 that in the Cambrian series, as defined by him more than a generation since, he 

 laid, on a sure foundation, the bases of Palaeozoic geology. 



intoticjes OIF 2!vd:E:]vnoii?/S. 



I. — Cakdiff Naturalists' Society: Eepokts and Tkansaotions. Vol. 

 III., Parts 1 and 2, for 1870-71 (1872), and Vol. IV. for 1872 (1873). 



AMONG a great deal of general information on Natural History 

 and scientific subjects, together with special descriptions of 

 local points of interest, in which antiquary, botanist a.nd geologist 

 are concerned, and a monthly series of valuable meteorological 

 reports by Mr. F. G. Evans, backed by tables of observations, we 

 find in these Transactions an elaborate and exhaustive memoir on the 

 Ehastic Beds of Penarth and Lavernock, by Mr. Etheridge, F.K.S., vol. 

 iii. part 2, pp. 39, etc., with two plates of fossils, and two of sections. 



