A HISTORY OF CORNWALL 



northern end of Constantine Bay is a new species of Conularla. It occurs 

 on the surfaces of the shales as nearly black flattened fragments, which 

 often retain the surface markings. In these surface markings this form, 

 according to Dr. Hinde, differs from all the other examples of Conularia 

 known from the Devonian rocks of America and Germany, principally 

 in the marked fineness of the transverse lines, and it probably belongs 

 to a new species. There was not a single example of this genus from 

 the Devonian rocks of this country either in the British Natural History 

 Museum or in the Museum in Jermyn Street in 1894, when some speci- 

 mens were given to them by Dr. Hinde. Two large pyritized forms 

 resembling Crustacea 15 to 18 inches long, were found here, one of 

 which is deposited in the Penzance Museum. 



The slates on the isthmus of Dinas Head show some organisms, 

 but the chief interest of this projection from Trevose Head is the ex- 

 posure of nearly an acre of a soda-felspar rock, weathering white, with 

 a chert-like appearance and fracture, and supposed to be a sedimentary 

 rock altered by contact with the igneous rock of which the peninsula 

 is composed. This rock contains about 10 per cent of soda. 1 Similar 

 porcellanized slates are seen in many of the greenstone promontories 

 north of this and at Lundy Beach near Port Quin, north of the Camel, 

 where the rock contains 9*35 per cent of soda and '39 per cent of 

 potash. 



East of Trevose Head lies Mother Ivey's Bay, where at the east end 

 of the beach a shelf of blue slate near high water mark has yielded Tenta- 

 cu/ites, small brachiopods, Centronella, a form allied to Retzia longirostris y 

 Orthoceras, and a specimen of Hyolitbes, all pyritized. This locality has 

 become famous recently by the discovery of a fragment of a large new 

 trilobite, Homalonotus Barratti, so named by Dr. H. Woodward, F.R.S., 

 in honour of the discoverer. 2 



We next reach Cataclews Point, famous for its variety of igneous rocks. 

 It gives its name to a stone that has been quarried for centuries for archi- 

 tectural purposes. The tomb of Prior Vivian in Bodmin church is an 

 example of its durability and value. It is a fine grained greenstone, for 

 the most part an altered picrite. Harlyn Bay is more famous for its pre- 

 historic cemetery than for older remains, and New Train Bay introduces us 

 to Trevone, which has proved a storehouse of interest. The fossils are 

 mostly pyritized, and unfortunately the scour of the sand is not sufficiently 

 severe to weather fresh fossils rapidly. Trevone cliffs and foreshore have 

 yielded Orthoceras^ Bactrites, Goniatites, Euompbalus, Tentaculites, trilobites, 

 corals, brachiopods, Styliola, and two fossils characteristic of Upper 

 Devonian rocks, viz. Bactrites budesheimensis, F. Roemer, and Cardiola 

 retrostriata, Von Buch. 3 



Trevone Bay is bounded on the north by Roundhole Point, and the 

 northern side of this promontory is composed of the noted ' Marble Cliffs, 



1 Described Geol. Mag, decade iv. vol. ii. No. 367, 1895. 

 Vide Geol. Mag. No. 463, January, 1903, pp. z8~3i. 

 3 Vide Trans. R. Geol. Sac. Corn. xii. 535-45. 



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