A. Somervail — Schists of the Lizard District. 161 



C. robustns, Newb., G. Phillipsii, Ag., C. Huxleyii, Traq., and G. 

 Tingleyensis, Davis, are transferred to a new genus, Rhabdoderma. 

 After a careful comparison of the species now described with the 

 typical C. granulosus figured by Agassiz, there does not appear any 

 generic difference in them to warrant such a separation. 



The Halifax Hard-bed Coal rests on the Ganister rock and Seat 

 earth used for making fire-bricks ; it is an impure Coal containing 

 iron in the form of pyrites, and not unfrequently nodules of the 

 same substance. Rounded concretions containing carbonate of lime 

 are also found in the Coal. Both contain vegetable remains in a 

 beautiful state of preservation ; when cut for microscopical exami- 

 nation, minute details of structure are exhibited with marvellous 

 fidelity. Immediately above the Hard-bed Coal is a stratum of 

 laminated shale, which is in some localities almost entirely com- 

 posed of the fossil shells of marine genera, including a large 

 proportion of Avicidopecten. The bed is about four inches in thick- 

 ness ; above, it is succeeded by a bed of shale four to six feet thick, 

 containing a considerable number of nodular concretions, composed 

 of carbonate of lime, with an outer covering of iron pyrites. These 

 when broken are found to contain great numbers of remains of 

 mollusca of the marine genera Goniatites, Nautilus, Bellerophon, 

 Orthoceras, Nucula, Avicidopecten, and others less common. Fossil 

 fish remains are also found associated, and it is in one of these balls 

 that the example of Ccelacanthus Phillipsii was found. Scattered 

 over the surface of the nodule are shells of Goniatites. From its 

 association with these marine mollusca there appears to be no doubt 

 that Ccelacanthus existed in salt-water during the formation of the 

 Lowest Coal-measures. This is interesting for comparison with 

 C. Tingleyensis, Davis, found in the Cannel Coal at. Tingley, which is 

 in the Middle Coal-measures. The Cannel Coal was deposited in a 

 series of lake-like lagoons, the bottom of which were filled with 

 fresh-water bivalves of the genus Anthracosia. The remains of 

 Ccelacanthus occur in great abundance, and it lived at this time in 

 fresh-water. The specimen of C. granulosus, Agass.. was obtained 

 from the Magnesian Limestone of East Thickley, in Durham, which 

 is of marine origin. 



V. — On thk Schists of the Lizard District. 



By Alexander Somervail, Esq. 

 Introduction. 



THIS paper is intended as preliminary to one shortly to follow on 

 the nature and origin of the banded structure in these rocks. 

 I have deemed it necessary to treat of the present subject as 

 introductory to the other, giving my own views as to what I believe 

 to be the true origin and relations of these rocks to each other, as 

 these seemed to me to have a very direct and important bearing on 

 the question of their banded structures. 



Under the term schists used in the title I include all the rocks 

 composing the " granulitic," " hornblendic " and " talco-micaceous " 



DECADE III. VOL. VII. NO. IV. 11 



