148 Hoicard Fox — Devonian Rocks and Fossils 



wliicli appeared to be of sufficient interest to justify figuring, 

 have been skilfully represented by Miss G. M. Woodward, and the 

 following notes are appended in explanation of thein, beginning 

 with the fish remains, 



Pteraspis Cormibica, McCoy, sp. (ri. VIT, Figs. 7, 8.) 

 This species is represented by irregularly shaped, flattened 

 fragments of the dermal plates, which are scattered, sometimes 

 singly, sometimes in close juxtaposition, and even occasionally 

 overlapping each other, on the exposed surfaces of the bluisb- 

 grey shales at Watergate Ba3\ The plates are black, sometimes 

 glossy in appearance, and their exterior surfaces are ornamented 

 with fine ribs or strias running parallel to tlie length of the plate. 

 The stria? are in places interrupted so as to look like a series of 

 minute tubercles, only visible under a lens, and in some instances 

 they are crossed transversely by lines of growth. The plates vary 

 from 0-5 to 1 mm. in thickness, and there are about four of the surface 

 stria? in a millimetre. These fragmentary plates have been identified 

 by Dr. Smith Woodward as similar to those of Fteraspis Cornubica 

 which occur in the Devonian rocks of Lantivet Bay, South Cornwall, 

 and of which he has lately given an interesting account (Trans. 

 Eoy. Geol. Soc. Cornwall, vol. xii, 1899, p. 229). 



These fragments are found at Bedruthan Steps as well as at 

 Watergate Bay. According to Dr. S. Woodward the genus Pteraspis 

 is characteristic of the Lower Devonian or Lower Old Ked Sandstone 

 in Western Europe, and does not descend below this horizon 

 (Catalogue of Fossil Fishes in the British Museum, vol. ii, 1891, 

 pp. 160-169). 



PldyctcBnaspis, sp. (PI. VII, Figs, o, 6.) 



The only specimen referable to this genus is a thin plate, part 

 of which is shown on the surface of a light-grey shale and pait 

 still enclosed in the rock. The plate is not entire ; in one direction 

 it is shown for a distance of o5 mm., and it is about 0-5 mm. in 

 thickness. The upper surface, nearly of the same grey tint as the 

 matrix, is furnished with numerous small depressed tubercles, 

 rounded or oval in outline, and about 0*5 mm. in diameter. They 

 are arranged alternately in rows, between three and four in the 

 distance of 2 mm. The summit of these tubercles is often wanting, 

 and the rounded dome is replaced by a minute crater. 



Dr. Smith Woodward states that owing to the incompleteness of 

 the plate it is not possible definitely to identif}' it with Phli/ctevnaspis. 

 but the tubercular surface is approximately similar to that of the 

 plates of P. acadica, Whit., sp. (see Gkol. Mag., Dec. Ill, Vol. IX, 

 1892, p. 5, PL I, Figs. 7, 8), from the Lower Devonian at Campbellton, 

 New Brunswick. The Canadian fossil, of which a specimen is in 

 the British Museum (Nat. Hist.), has stouter tubercles with stria? 

 radiating from their bases, and they are more deeply hollowed out 

 than in the present form. 



The specimen is from Watergate Tiay. The genus Pldijctmiasins 

 is characteristic of the Lower Old Ked or Lower Devonian. 



