No, 3.] HUNT— ON CAMBRIAN AND SILURIAN. 309 



green and purple sandstones with conglomerates, shales and some 

 clay-slates. They occasionally hold flakes of anthracite, and 

 small portions of mineral pitch exude from them in f-ome local- 

 ities. The only evidence of animal life yet found in the rocks of 

 the Longmynd are furnished by worm-burrows, the obscure re- 

 miins of a crustacean, (the P doenpijge Rnnmi/}\) and a form 

 like Hlstioderma. This latter organic reiic, with worm-burrows, 

 and the fossils named Oldhamifi, is found on the coast of Ireland 

 opposite Caernarvonshire, in the rocks of Bray Head ; which 

 resemble lithologically the Harlech beds, and are regarded as 

 their equivalents. 



Still another area of the older rocks is that of the Malverji 

 hills, on the western flanks of \^hich, as already mentioned, the 

 Lingula-fl.igs are represented by about 500 feet of black shales 

 with Olenus, underlaid by 600 feet of greenish sandstones con- 

 taining traces of fucoids, with Serpulites and an Obolella. It is 

 not iniprob:ible, as suggested by Barrande and by jMurchison, 

 that these 1100 feet of strata represent, in this region, the great 

 mass of the Lingula-fligs, — and, we may add, perhaps the whole 

 series of Lower C mbrian strata, which in Caernarvonshire and 

 Pembrokeshire underlie them ; since these sandstones of M>.lvern, 

 like those of St. David's, rest upon crystalline schists, and are iu 

 part made up of their ruins. 



These crystalline schists of Malvern, which are described by 

 Phillips as the oldest rocks in England, and by Mr. HoU are con- 

 jectured to be Luurontian, seem from the descriptions of their 

 lithological characters to resemble those of Caernarvon and Ang- 

 Icsea, with which they are, by Murchison, regarded as identical. 

 The crystalline schists of these latter localities are, by Sedgwick, 

 described as hypozoic strata, below the base of the C imbrian. 

 Murchison however, in the first edition of his Siluria, adopted the 

 suggestion of Dj la Beche that they themselves were altered 

 Cambrian strata. In fact they directly underlie the Llandeilo 

 rocks, and were apparently conceived by Murchison to represent 

 the downward continuation of these, upon which he had insisted. 

 This opinion is supported by ingenious arguments on the part 

 of Ramsay. [Mem. Geol. Survey, III, part 2, passim.] I am 

 however disposed to regard them, with Sedgwick and Phillips, as 

 of pre-Cambrian age, and to compare them with the Huronian 

 series of North America, which occupies a similar geological 

 hori;zon, and with which, as seen iu northern Michigan, and in the 



