a Gigantic Animal of the Pterodactyle hind. 281 



being too much abraded to give evidence of zjgapopliyscs or 

 neural spine, or the extent of the transverse processes. 



Tlie posterior articuhition is vertically ovate and well cupped; 

 seen from the side, its outline is concave, so as to admit (ap- 

 parently) of lateral motion upon the adjacent centrum. In 

 front the body of the vertebra is rather larger than it is behind, 

 and convex ; but it has been worn S(j that the whole of the 

 external layer of bone over the anterior articulation has been 

 removed : it was of paper thinness, as in the Pterodactyles. 

 Wherever this external lilm is wanting is seen either an abso- 

 lute cavity or enormous honeycomb-like cells of irregular 

 Solygonal form, for the most part long in the direction of the 

 epth of the centrum, and divided l>y exceedingly thin and 

 compact films of bone, which extend towards the articular 

 ends of the vertebra. 



In the middle of the upper part of the side of the centrum, 

 below the level of the neural canal, is an enormous subtrian- 

 gular hole lined with a continuation of the external bone for 

 some distance inward. It is more than a third of the length 

 of the centrum, longer than high ; its upper angle is above 

 the level of the base of the neural canal ; and it narrows to- 

 wards the concave end of the centrum. This large hole, be- 

 tween three and four inches long, is situate precisely as are 

 the pneumatic foramina of Pterodactyles, and in this specimen 

 is regarded as a pneumatic foramen which supplied the bone 

 with air from the lungs after the plan of the class of birds. 



In front of it the combined centrum and neural arch widen 

 rapidly, as though for the attachment of a rib, though possibly 

 the thickening may be only such as characterizes the neck- 

 vert ebrie of birds. 



The external surface is dense and smooth, and gently concave 

 from front to back, where the margin of the posterior cup is 

 prominent. From above downward the sides are convex, and 

 approximate in a natural compression so as to form an inferior 

 mesial antero-posterior ridge. 



The neural canal posteriorly is subovate, higher than wide, 

 and about three inches high. 



The lateral compression of the centrum is altogether avian ; 

 and in the anterior enlargement it resembles birds rather than 

 Pterodactyles, though herein recalling certain Dinosaurs. The 

 opisthocoelous centrum may be matched among mammals, 

 Dinosaurs, and a few natatorial birds. 



In the ' Geology of the South-east of England,' Dr. Man- 

 tell figured, at pi. 2. fig. 5, a bone which he describes as the 

 tympanic bone of Iguanodon^ at pp. 305, 306 of that work. 



Ann. d: Mag. N. Hist. Ser.4. VoI.y, 19 



