1887.] Meiolania platyceps. Dynamical Principles. 297 



III. " On Parts of the Skeleton of Meiolania platyceps (Ow.)." 

 By Sir Richard Owen, K.C.B., F.R.S., &c. Received March 

 29, 1887. 



(Abstract). 



The subjects of the present paper are additional fossil remains of 

 Meiolania platyceps from Lord Howe's Island, transmitted to the 

 British Museum since the author's previous paper on the subject. 

 Additional cranial characters are denned and illustrated by drawings 

 of more or less perfect specimens of the skull, of vertebrae of the 

 neck, trunk, and tail, of limb-bones, and portions of the dermal 

 skeleton. 



The author sums up the affinities, deducible from the above parts of 

 the skeleton, to the orders Chelonia and Sauria, with grounds for the 

 conclusion that the genera Megalania and Meiolania are more nearly 

 akin to the Saurian division of the class Reptilia, in which he proposes 

 to refer those extinct genera to a sub-order called Geratosauria. 



IV. " Some Applications of Dynamical Principles to Physical 

 Phenomena. Part II." By J. J. Thomson, M.A., F.R.S., 

 Fellow of Trinity College and Cavendish Professor of 

 Experimental Physics in the University of Cambridge. 

 Received March 31, 1887. 



(Abstract.) 



This is a continuation of a paper with the same title published in 

 the ' Phil. Trans.,' 1885, Part II. In the first paper dynamical 

 principles were applied to the subjects of electricity and magnetism, 

 elasticity and heat, to establish relations between phenomena in these 

 branches of physics. In this paper corresponding principles are 

 applied to chemical and quasi- chemical processes such as evaporation, 

 liquefaction, dissociation, chemical combination, and the like. 



Many of the results obtained in this paper have been or can be 

 obtained by means of the Second Law of Thermodynamics, but one of 

 the objects of the paper is to show that there are other ways of 

 attacking such questions, and that in many cases such problems can 

 be solved as readily by the direct use of dynamical principles as by 

 the Second Law of Thermodynamics. 



A great deal has been written on the connexion between the 

 Second Law of Thermodynamics and the principle of Least Action ^ 

 some of these investigations are criticised in the first part of the 



