550 Reports & Proceedings — The Royal Society. 



less than might have been expected. The Elham and Folkestone 

 borings show the south-westerly thickening of the Wealden (153 feet 

 and 218 feet respectively), but each apparently demonstrates the 

 entire absence of both Purbeck and Portland rocks. 



Mr. Gr. W. Lamplugh (Appendix IV) discusses the underground 

 range of the Jurassic and Lower Cretaceous rocks in East Kent, and 

 is more fortunately situated than the present writer (who has been 

 away at sea) in having information furnished by a further twelve 

 borings to work upon. 



November 14, 1917. 



EEPOETS AITDPEOCEEDIlSrGS. 



I. — The Royal Society. 

 November 8, 1917. — Sir J. J. Thomson, O.M., President, in the Chair. 



The following paper was read : — 



"The Structure, Evolution, and Origin of the Amphibia. Part I : 

 The 'Orders' Rachitomi and Stereospondyli." By D. M. S. "Watson, 

 M.Sc, Lieut. R.N.V.R. (Communicated by Professor J. P. Hill, 

 E.R.S.) 



In this paper all known genera of Rachitomous and Stereo- 

 spondylous Stegocephalia are reviewed, the brain-case and basi-cranial 

 region, hitherto practically unknown, being described more or less 

 completely, and much new information about other regions set down. 

 It is shown that there are a series of characters which change 

 steadily with time in all Labyrinthodontia. The more important of 

 these changes are — 



1. The gradual reduction and final loss of basi-occipital, basi- 

 sphenoid, and supra-occipital bones and cartilages. 



2. The gradual replacements of basi-pterygoid processes of the 

 basi-sphenoid by expansions of the para-sphenoid, and finally of the 

 ex-occipitals with which the pterygoids articulate. 



3. The gradual increase in size of the inter-pterygoid vacuities, 

 and of the para-sphenoidal rostrum. 



4. The gradual regression and final disappearance from the skull 

 of a foramen for the hypoglossal nerve. 



It is pointed out that these characters, which are seen to arise 

 within these two groups, are those which have always been regarded 

 as the diagnostic features of the class Amphibia, and that it is certain 

 that they have arisen independently in at least three great orders. 



Finally, it is shown that a hypothetical ancestor of the Rachitomi 

 obtained by projecting backward the evolutionary trends shown in 

 these and other series of characters which change regularly with 

 time, is actually realized in the Embolomerous Amphibian Pteroplax. 



II. — Geological Society of London. 

 November 7, 1917.— Dr. Alfred Harker, F.R.S., President, in the 



Chair. 

 The following is an abstract of a lecture on " The Nimrud Crater 

 in Turkish Armenia" delivered by Felix Oswald, B.A., D.Sc, 

 F.G.S. :— 



