496 Dr. Whcelton Bind 8f John T. Stobbs— 



Fig. 



8. ? Thracia sp. Natural cast of an imperfect left valve showing external 



features. Nat. size. 



9. Astarte Giithriensis, sp. nov. External ^•iew of right valve, x 2. 



10. A. Gitthritttfis, TAT. Outer view of a right valve, x 2. 



11, 12. A. Scriveuori, sp. nov. External views of right valves. Fig. 12 drawn 



from a wax cast of original cavity. Nat. size. 



13. CucitUcea Scvivmori, sp. nov. External view of right valve, x 2. 



14. Area sp. External view of a natural cast of a right valve. Nat. size. 



15. ? Zf<d';irt sp. Outer aspect of a fragmentary right valve, x 2. 



16. Fodozamites cf. lanceolatus. An incomplete i)inna showing the prohable base 



as tapering to a point where attachment to the rachis might have been 

 effected. Nat. size. 



17. I'odozainifes cf. lanceolafits. A more imperfect fragment of another pinna with 



an obscure indication of a basal notch, x 2. 



18. Carpolithcs sp. Longitudinal view of a seed showing on the right margin the 



renuuus of a possible outer integimient. x 2. 



Xote. — Specimens represented by Figs. 3, 4, and 17 were collected and presented 

 to the British Musevim by Dr. R. llanitsch ; the remainder were collected by 

 Mr. J. B. Scrivenor and similarly presented by him to the same institution. 



III. — The Carboniferous Succession below the Coal-Mbasures 

 IN North Shropshire, Denbighshire, and Flintshire. 



By Whebiton Hind, M.D., B.S., F.R.C.S., F.G.S., and John T. Stobbs, F.G.S. 



{Concluded from the October Number, p. 459.) 



5. Comparison of the Pal^siontoloqical Sequence of the 



Carboniferous Rocks of North Wales with that which 



occurs in other Carboniferous Areas in England and 



Wales. 



The paljeontological succession of the Carboniferous rocks of 



North Wales is practically identical with the succession in the 



Pennine ai-ea, and to a certain extent with that which obtains in the 



Bristol-Meudip area. 



Dr. A. Vaughan has demonstrated that in the latter district the 

 distribution of the Corals and Brachiopoda aflfords a definite basis for 

 the subdivision of the Carboniferous Limestone into life-zones (Quart. 

 Journ. Geol. Soc, vol. Ixi, pp. 180-307). We have found the corals 

 most valuable indices during our work in North Wales. Apparently 

 the vertical distribution of the Carboniferous corals demonstrates 

 a progressive evolution, and both genera and species have a definite 

 vertical range and are therefore time indices. They can on that 

 account be safely relied upon for the correlation of beds in faulted or 

 widely separated areas. Witli regard to the Brachiopoda, here again 

 within limits certain definite mutations cf a form, which evidently 

 have a certain genetic relationship, appear only at particular horizons 

 and have a definite vertical range. Unfortunately many of the 

 names of the Brachiopods selected by Dr. Vaughan as the zonal 

 indices belong to species which were founded on specimens which 

 occurred at much higher horizons than those to which he would 

 have referred them in the Bristol area. They are therefore the last 

 mutation of the genus of the peculiar species rather than one of 



