114 /. JF. Ecam Sf R. W. Pocock—Age of the Morte Slafes. 



a distinctly slaty facies, M'liicli presents a close resemblance to the 

 normal Morte Slates of this area. 



Spirifer Hamlingi must be classed with the ' aperturati ' group of the 

 genus and is undoubtedly a varietal form of Sp. Verneuili, Murch. 

 \=disjiinctus, Sow.). The fold and sinus are distinctly marked off 

 from the side portions of each valve, and the sinus is narrower and 

 deeper than it is in other varieties of the species. The number of the 

 plications in the fold and sinus is about twelve. The valves are not 

 distinctly winged, and the ratio of the breadth to the length is 

 approximately four to three, the former measuring in the larger 

 specimen a little more than 22 mm. and the latter nearly 17 mm. 

 These figures may, however, be somewhat modified when the matrix 

 is cleared from the specimen. 



Closely similar but somewhat larger specimens in the British 

 Museum (Natural History) are labelled "near Taunton". They are 

 in a reddish-yellow grit, and were, Mr. TJssher believes, those described 

 by the Eev. W. Downes (Trans. Devon. Assoc, 1881, pp. 293-7), which 

 were found in New Eed gravels at Bolham, and may have been 

 derived from the Pilton Beds which outcrop to the northward. 

 Gosselet figures a somewhat narrower form from the Schistes de 

 Senzeilles (zone of Rhi/ncJionella Omaliusi) at the base of the 

 Famennian (Mem. Soc. Geol. Nord, vol. iv, pt. i, p. 30 and fig. 38, 

 1894), and a variety figured by G-. and F. Sandberger under the 

 name of Sp. calcaratus (Sow.) (Verstein. rhein. Schicht. Wiesbaden, 

 1850-6, pi. xxxi, figs. 10, 10«-10c) also presents many points of 

 similarity. It may be added that no representatives of the species 

 are found on the Continent lower than the passage beds between 

 the Middle and Upper Devonian. 



On one of the slabs there are also specimens of a Rhynchonella, 

 which is probably identical with the form obtained by Hicks from 

 the same locality and identified bj- him as Rh. Leivisi, Dav. They 

 appear to resemble Rh. {Camarotoechia) ferqimisis^ Gosselet, from the 

 Lower Frasnian of Belgium and the Boulonnais, and Rh. ktietisis, 

 Gosselet, from the Tipper Famennian, two closely allied forms which 

 were formerly included in Rh. pleurodon, Phil., into which the latter 

 is believed by Gosselet to pass at the commencement of the 

 Carboniferous period (Ann. Soc. Geol. Nord, vol. xiv, pp. 199 and 

 206, 1887). 



There is therefore a prima facie case for placing the Morte Slates of 

 Barricane Beach in the Upper Devonian and for regarding the apparent 

 succession of the rocks on the coast of North Devon as the true one. 

 At the same time it must be admitted that whenever the southern 

 margin of the Morte Slates in North Devon has been examined there 

 appears to be evidence of disturbance which renders it possible that 

 there has been considerable dislocation of the strata along this line. 

 This is, however, only what usually occurs at the junction of rocks 

 which differ considerably in their physical characters in an area 

 which has been subjected to powerful earth-movements, and does not 

 imply that the faulting which may have taken place represents 

 a large relative movement of the beds, and in the Marine Drive at 

 Woolacombe there appears to be distinct evidence of a transition 



