273 



ment, and the coordinates of the fixed plane upon which the move- 

 ment takes place, are found by means of formulae of remarkable 

 simplicity. These three quantities may be ascertained once for all 

 for each planet (viz. the inclination of the fixed plane on which the 

 node moves to any coordinate plane, the longitude of the node of the 

 fixed plane in relation to any coordinate line, and the angular rate of 

 movement of the node of the orbit upon this fixed plane), and, when 

 once ascertained, may be regarded as fixed elements of the planet, 

 from which the position of the plane of its orbit can always be deter- 

 mined without the use of tables. 



II. "Description of some Remains of a Gigantic Land-Lizard 

 (Megalania prisca, Ow.) from Australia." By Prof. 

 RICHARD OWEN, F.R.S. Received May 13, 1858. 

 (Abstract.) 



The subject of this communication forms part of a collection of 

 fossil remains from Australia, recently acquired by the British Mu- 

 seum, and demonstrates the former existence in that continent of a 

 land-lizard considerably surpassing in bulk the largest species now 

 known. The characters are chiefly derived from vertebrae, partially 

 fossilized, equalling in size those of the largest existing Crocodiles ; 

 they are of the 'proccelian' type, but present lacertian modifica- 

 tions, and closely agree with those in the great existing * Lace- 

 lizard ' of Australia (Hydrosaurus giganteus, Gray), of which indi- 

 viduals upwards of six feet long have been taken. A generic or sub- 

 generic distinction is indicated by the comparatively contracted area 

 of the neural canal, and by the inferior development of the neural 

 spine, of the fossil vertebrae, which have belonged to an indivi- 

 dual not less than twenty feet in length, calculated from the vertebrae 

 and proportions of the body of the existing Hydrosauri. For this, 

 probably extinct lizard, the name of Megalania prisca is proposed. 



The results of an extended series of comparisons of its vertebrae 

 with those of recent and extinct Sauria are given ; and the paper is 

 illustrated by drawings of the vertebrae of Megalania and those of 

 Hydrosaurus. 



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