Additional Note on Ctenodus. 317 



IV. — Note on a Tooth of Ctenodus tuberculatus in the 

 Bkitish Museum. By the Editor. 



(PLATE IX. Fig. 3.) 



Having had our attention directed by Mr. Barkas's paper to the 

 specimens of this genus in the National Collection, and com- 

 pared Mr. Barkas's figures with Mr. T. Atthey's description of 

 Ctenodus tuberculatus [see " Annals and Magazine of Natui-al His- 

 tory" (4th series), Feb. 1868 (p. 83)] ; Mr. W. Davies having also 

 kindly pointed out to us a small but very perfect palatal tooth (see 

 Plate IX. Fig. 3), probably from the Coal-measures of Carluke (from 

 the collection of the late Mr. Alexander Bryson of Edinburgh), 

 closely agreeing with Mr. Atthey's description in all its characters ; 

 we have thought it well deserving of a place in our Plate. 



At the same time we may state that there is no reason why Figs. 

 1 and 2 on Plate IX. may not also belong to the same species as 

 suggested by Mr. Barkas, as the teeth of this genus appear to be 

 subject to considerable individual variation. 



The annexed description is taken from Mr. Atthey's paper above 

 referred to (op. cit. p. 83) : — 



" Ctenodus tuberculatus, n. sp. — Tooth plate-like, thick, with an 

 irregular ovate outline, 2f inches long, l-|-th inch broad, the 

 narrow end posterior; the inner margin gibbous or angulated in 

 the centre ; the outer margin a little convex ; the surface is slightly 

 convex, and is furnished with twelve or thirteen deep, sharp, parallel, 

 approximate ridges, which are strongly tuberculated towards the 

 outer margin, and divided by narrow, deep, angulated grooves ; they 

 are arched posteriorly and enlarged towards the exterior border, but 

 do not at all assume a radial arrangement, the anterior ridge, which 

 is wider than the others, is reflected and prolonged for some distance 

 beyond the outer margin ; the tubercles are conical, with obtuse 

 points ; those next the external border are coated with shining 

 enamel, and are well produced." 



Besides the specimen figured (Plate IX. Fig. 3), there are in the 

 British Museum several fine teeth belonging to this genus (probably 

 also from Carluke), and a portion of the head and lower jaw with 

 both the upper teeth and one lower (or mandibular tooth) in situ 

 from the Coalfield of Airdrie. 



V. — The Lead-Beahing Distkicts of the Nokth of England.^ 

 By Prof. Morris, F.G.S., etc. 



THE district to which attention is directed is situated in the centre 

 and the most elevated part of Great Britain, which is thickly 

 inhabited by an industrial population, many of whom are occupied 

 in the working of Lead-mines. The Agent's house of the Beaumont 



' Being the substance of a Lecture delivered before the Geologists' Association at 

 University College, London, by Prof. Morkis, F.G.S., the President of the Asso- 

 ciation, on June 4th, 1869. 



