WEALDEN CROCODILES. 627 



Order. CEO COD ILIA. 

 Family. CCELOSPONDILIA.* 



Ge7ius — PoiKiLOPLEURON. Eucles-DeslongcliampsA (' Crocodilia,' Plate 39.) 



This genus was established on fossils discovered in the Oolitic building-stone at Caen, 

 Nornaandy, and the characters which have led to the recognition of evidences of the 

 genus in our own Wealden deposits are the shape and texture of the vertebrae, and more 

 especially the latter. By these were determined a caudal vertebra from the Wealden of 

 Tilgate, in the Mantelhan collection, now in the British Museum : which vertebra differed 

 from the type-specimens on which the genus was founded, only by a shght inferiority of 

 size. 



M. Deslongchamps assigns the length of a ' decimetre,' or thereabouts, to his vertebrae, 

 say 3 inches, 10 lines. The Wealden specimen, which has been fractured across the 

 middle of the centrum, gives a length of that element of 3 inches, 8 lines ; or about 9 

 centimeters. The vertical diameter of the articular end is 2 inches, 3 lines (58 mm.), 

 the transverse diameter is 2 inches, 2 lines (55 mm.) ; the transverse diameter of the 

 middle, contracted part of the centrum is 1 inch, 4 lines (30 mm.). 



The external free surface of the vertebra is marked with faint striae, otherwise it is 

 almost smooth. Both terminal surfaces are of a full elliptical form, with the long 

 diameter vertical; they deviate from flatness by a slight concavity. The centrum 

 gradually contracts from the two extremities toward the middle : a diapophysis 

 extends from the upper and hinder part of the side, below which there is a shallow 

 groove, slightly bent with the convexity downward. The neural arch has coalesced with 

 the centrum, and the base of the diapophysis extends from the hinder upper half of the 

 centrum upon the base of the arch. A longitudinal sulcus traverses the anterior half of 

 the under surface of the centrum. The hypapopbysial surface is a single obliquely bevelled 

 plane indicative of the confluent bases of the hasmapophyses, and this is the character of 

 the haemal arch preserved in the Caen specimen. 



In my 'Report on British Fossil Reptiles'! I did not recognise grounds for 

 specifically difl'erentiating the Wealden Poikilojjleuron from the Poik. Bucldandi of the 



* This terra refers to the large vacuity in the centre of each vertebral body, simulating a medullary 

 cavity ; ossification is here arrested at the middle, not, as in the Amphica-lia, at the two ends of the 

 centrum. 



t 'Memoires de la Societe Linueenne de Normandie,' vol. vi, 1838, p. 37. 



X ' Reports of the British Association,' 1841, p. 84. 



in 



