﻿2 



FOSSIL REPTILIA OF THE 



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 hypapophysia] surface is a single obliquely bevelled 

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

 the haemal arch preserved in the Caen specimen. 



In my ' Report on British Fossil Reptiles 51 I did not recognise grounds for 

 specifically differentiating the Wealden Poikilopleuron from the Poik. BucMandi of the 

 Caen Oolite. Besides the Tilgate locality I was able to note, after examination of a 

 series of fossils belonging to S. H. Christie, Esq., from the submerged Wealden Beds, 

 Isle of Wight, the " half of a dorsal vertebra from Brook Bay, which agrees in size, in 

 the form of the articular extremity, in the degree of median constriction, and especially in 

 the large size of the medullary" (chondrosal) " cavity at the middle of the bone, with the 

 vertebral characters of Poikilopleuron."* 



Species. Poikilopleuron pusill us, Ow. Plate I. 



This species is, to me at present, represented by eight vertebrae, an ungual phalanx 

 of the rapacious type, and part of a medial symmetrical bone to which are articulated 

 portions of a pair of rib-like bones, as to the nature of which the nearest guess I can 

 make is that they represent part of the series of abdominal ribs with their sternum. 



All these bones show a compact osseous texture with a smooth or polished exterior, 

 and a section of one of the dorsal centrums exposed, what a fractured caudal one 

 indicated, viz. a large central chondrosal vacuity, such as characterises the centrum of 

 the Oolitic crocodilian genus Poikilopleuron of Eudes-Deslongchamps. 



The reptile, of which the present are fossilised remains, was discovered by the Rev. 

 W. Fox, M.A., in the south-west Wealden of the Isle of Wight ; it is much smaller 

 than the type of the genus Poikilopleuron from the Caen Oolite, or the Wealden vertebrae 

 above referred to Poik. BucMandi. It may be objected that the present specimens are 

 from a young individual of the same species ; but they show no signs of immaturity, and 

 the caudal hypapophyses indicate the bases of the piers of the haemal arch not to have 

 been confluent as in the Poikilopleuron BucMandi, and as in Iguanodon. 



The vertebral centrums are long in proportion to their breadth and depth, and 



1 ' Reports of the British Association,' 1811, p. 84. 2 lb., p. 87. 



