TRANSACTIONS OF THE SECTIONS. '55 



aci'ogenoiis stems tell of the arborescent ferns that floated tlieir plume-like foliao-e 

 on the islands of the Carboniferous period, and the industry and^genius of the man 

 ■who has collected and preserved them for our instruction and delight. The animal 

 remains are here very scarce ; two or three species of the genus Linmhis, and one or 

 two Anthracosice, are all that have been found : and I have the satisfaction of addim- 

 that I am authorized to say that by previous arrangement Mr. M'Mm-trie will be 

 happy to show his Museum to any Members of the Association to whom the same 

 might be interesting. As there will be, I understand, memoirs on the Radstock 

 Coalfield, I must refer to these papers for further details on this interesting district. 



4. The Beistol Distbict. 



In a radius of eight miles from the Guildhall we find exposures more or less com- 

 plete of the following PalaBozoic and Mesozoic formations : — 1. The Old Red Sand- 

 stom; 2. The Carboniferous Limestone ; 3. Millstone Grit ; 4. Coal Measures ; 5. Dolo- 

 mitic Conglomerate and Netu Red Sandstone ; 6. Rlmtic ; 7, Lias, Lower, Middle, 

 Upper; 8. Upper Lias Sands; d. Inferior Oolite; 10. Fuller's Uarth ; 11. Great 

 Oolite; 12. Alluvium, with igneous rocks of Palaeozoic age. Several of these for- 

 mations I have ah-eady noticed in speaking of the Mendip Hills ; therefore I shall 

 now only add such special remarks as are required to complete their sketch in the 

 Bristol district. 



The Old Red Sandstone forms, as we have seen, the axis of the Mendip Hills, and 

 here occurs as a massive rock in difterent regions of the Bristol Coal-field, formiuo- 

 ranges of hills that have been sculptured by denudation out of its anticlinal folds'. 

 The beds in general are very unfossiliferous. 



In the neighbourhood of Portishead, however, the remains of some large fishes 

 have been found in a hard conglomerate, belonging to the genus Holoptycliius — 

 reminding us of the fishes of the Old Pied Sandstone of Scotland, which were all 

 encased in a bony armour, and possessed some of tlie most remarkable forms of the 

 ichthyic type. Pterichthys or wing-fish, Holoptychius or wrinkle-scaled fish, Cepha- 

 laspis or buckler-shielded fish are all forms of the Old Red, and the earliest repre- 

 sentatives of the class Pisces in the Palspozoic rocks. 



The Carboniferous Limestone is a great marine formation, and is formed of the 

 sediments of an extensive and wide-spreading sea ; the beautiful scenery so charac- 

 teristic of the Avon, Severn, and Wye is in a great measure due to the development 

 of this rock in these regions. One of the grandest sections of all the beds of the Car- 

 boniferous Limestone is that exposed in the gorge of the Avon near Clifton, where it 

 is seen resting on the Old Red Sandstone, and overlain by the Millstone Grit. 



The various conditions of the old sea-bottom in which this mass of calcareous 

 rock was formed may here be studied with ease. The entire thickness of the strata 

 exposed is upwards of 4000 feet ; of this the Old Red Devonian is 768 feet, the Car- 

 boniferous Limestone 2338, and the Millstone Grit 9o0 feet. This magnificent section 

 has repeatedly been the subject of memoirs by Buckland*, Conybearet, Bright f, and 

 "Williams§, who have given ample details of all its different beds. 



The Lower Lirnestone Shales, 500 feet in thiclcness, are very fossiliferous ; they 

 consist of alternations of shales and limestone, with a bone-bed near their base ; in 

 some places beds several feet thick are formed of the ossicula of Crinoids. In the main 

 Limestone series you have a succession of Brachiopoda ; Spirifera, Producta, and 

 OrthisioWo^ each other. Of Lamellibranchs we iini Aiuadojjecten, Cardiomorpha, 

 &c., with Gasteropods, as Euomphalus and Bellei-ophon, and Cephalopods, as Goniatites, 

 Orthoceras, Actinoceras, &c. To these may be added the teeth and defensive spines 

 of large shark-like and other fishes, as Cladodus, Psammodus, Orodus, Holoptychius, 

 &c. Some of the coral strata in the upper part of the series are very interesting, and 

 extremely rich in very beautiful specimens of Actinozoa, belonging to the reef-buildiu"- 

 groups of the ancient sea, as Michelinia, Amplextis, Lifhostrotion, Syrinyopora, Lons- 

 daleia &c., reminding us of the structure of coral reefs in our present seas. Asso- 



* " On the South- Eastern Coal District of England," Geol. Trans. 2nd series, vol. i. ; 

 1" Geol. Trans. 1st series, vol. ir. . 



X " On the Limestone Beds of the Eiver Avon," Geol. Trans. Ist series, vol. v. 

 § ' Memoirs of the Geol. Survey,' Sir H. De la Beche's Essay, vol. i. p. 113. 



