GEOLOGY OF PART OF SOUTH DURHAM. 179 



the general direction in which occurred our opportunities of ob- 

 servation. Further away in the same course (J J J) the roof is 

 formed of dark grey shale which is almost barren of plant re- 

 mains, the only exceptions being the very occasional presence 

 of Calamites approximates or of Lepidodendron selaginoides, but 

 which contains more frequently specimens of the supposed mar- 

 ine shells Anthracosia acuta, and Anthracoptera sp. The roof 

 would appear to maintain this character over a wide district ; 

 and in one place, almost three miles away from the localities H 

 and /, there are the remains of fish in the shape of teeth and 

 scales of the well-known Megalichthys Hibberti. 



"Within, however, the limits of this roof with Anthracosia acuta, 

 there occurs, at the spot marked K, a curious little oasis, as it 

 were, of vegetable fossils, where the remains of Calamites appro- 

 ximatus, Lepidodendron sp., and Lepidodostrobus, are seen in com- 

 parative profusion. 



At another point nearly two miles north of A we obtained 

 from shale from the roof of the Brockwell many species of fossil 

 plants. Among others the following : — Lepidodendron selagi- 

 noides, Neuropteris Loshii, N. heterophylla, N. acuminata, Splie- 

 nopteris ajftnis, 8. bifida, 8. crenata, S. multifida, Pecopteris 

 Bucklandi, Alethopteris lonchitidis, Sphenophyllum erosum, Aste- 

 rophyllites foliosus, Antholithes Pitcairnia, and many other spe- 

 cies, more especially of ferns. But the prevailing fossil of this 

 locality is Lep. selaginoides. 



Five Quarter Seam : — 



At the point marked A and B (diagram II.) the coarse coal 

 or bratt lying above the seam, with a portion of the roof above, 

 are full of compressed impressions of the fluted stems of Sigil- 

 laricB, to the exclusion of other species. In some places the 

 upright stools of the same tree appear. 



At C the roof, for some feet upward, is one mass of the com- 

 pressed stems of Sigillaria and Stigmaria, without traces of 

 other fossils. 



At D the remains of Sigillaria are still common, but those of 

 Calamites approximates are almost equally so. Ferns belonging 



