444 Br. C. W. Andrews — The Fore-limb of Metriorhynchus. 



and the melting action of its summer warmth, why should this gravel 

 not be found over the whole of Southern England, instead of being 

 confined to the glacial depression-districts of the south coast ? 



(To be concluded in our next Number.) 



III. — Note on a Pore-paddle op Metriorhynchus prom the 

 Oxford Clay of Peterborough. 



By Charles W. Andrews, D.Sc, F.B.S. (British Museum, Nat. Hist.). 



Published by permission of the Trustees of the British Museum. 



IN the description of the skeleton of Metriorhynchus given in 

 vol. ii of the Catalogue of the Marine Eeptiles of the Oxford 

 Clay, very little could be said about the fore-limb. The only parts 

 then known were a number of humeri and, in one or two cases, some 

 small disc-like bones which were regarded as the radius and ulna : 

 the most complete fore-limb was figured on p. 172 of the volume 

 quoted. In order in some degree to fill this gap a short account was 

 given (torn, cit., Introduction, p. xiii) of an imperfect fore-paddle of 

 a specimen of the closely related Geosaurus gracilis from the Solenhofen 

 limestone. This beautiful skeleton, originally described by V. Ammon 

 {Geognostische Jahreshefte, vol. xviii, p. 12), has recently been 

 acquired by the British Museum, and a photograph of it is given as 

 a frontispiece to vol. ii of the Catalogue of Oxford Clay Reptiles. 

 The specimen is beautifully preserved, and is remarkable for showing 

 the outline of the tail-fin and other traces of the soft parts. 

 Unfortunately for the present purpose the fore-limb is represented 

 only by impressions of the bones, and no trace of the humerus can be 

 seen, but still a good idea of its short paddle-like structure is given : 

 this is shown in figure 1. 



Pig. 1. — Fore-paddle of Geosaurus gracilis, a. radius ; b. ulna ; c. radiale ; 

 d. ulnare ; mc. 1-4, metacarpals. B 3948. Nat. size. From Catalogue of 

 the Marine Reptiles of the Oxford Clay, p. xiii. 



It will be seen that proximally there are two pairs of disc-like 

 bones, the homologies of which are not certain. Ammon regards the 

 proximal pair (« and b) as being the radius and ulna, the distal pair 

 (c and d) as the radiale and ulnare. Fraas in his account of the 

 fore-limb of Geosaurus adopts the same view (Palceotitographica, 



