384 MR. E. W. HOOLtY OX THE [June I913, 



The Sacrum. 



Unfortunately, only the fused centra of three, and a portion of 

 the fourth, sacral vertebrae are preserved. They gradually lessen 

 in dimensions posteriorly. The bases of the transverse processes 

 are all that remain, and it is impossible to determine the form of 

 the sacrum. 



Vertebral Ribs. 



Vertebral ribs were lying among the bones near the notarium. 

 They were much waterworn. They are short, small, and hollow, 

 and are two-headed as in other Ornithosaurs. 



The Sternum. 

 There is no styliform anterior process of the sternum (PI. XL, 

 fig. 3) such as in all other types is greatly prolonged anterior to the 

 coracoid facets. The keel is as remarkably developed as in the 

 carinate birds. The anterior border is almost vertical ; although, 

 ventrally, it bulges slightly in front of the coracoid articular facets. 

 The longitudinal outline rises posteriorly with a sharp curve, and 

 has a greater length than depth. At the posterior end it is a little 

 blunted, by the breaking-away of the rind of the bone. It is very 

 robust, especially at the anterior end. In the lateral median 

 region it becomes gently concave. The base of a strong bony 

 process occurs near the centre of each lateral border, and appears 

 to have been produced upwards and dorsally to them. Although 

 the edge of the lateral expansion is broken away, the converging 

 surfaces of the bone are divided by so narrow a space that they 

 -could not have been produced more than a fraction farther. 

 Through this the costal facets are not seen. If they were present, 

 they could only have occupied 18 mm. of the edge, for the rest of 

 the border is too thin and angular for the sternal ribs to have 

 articulated there. The dorsal surface is concave. There is a 

 broadening of the fore part of the keel for the coracoid facets, which 

 are placed below the sternal plate (PI. XL, figs. 3 & 4, cor.ar.fa.). 

 The right coracoid facet is situated 20 mm. below the sternal plate 

 and 42 mm. above the ventral outline of the keel. In Seeley's 

 figure of this sternum x the coracoid facets are incorrectly depicted 

 as being on the same plane as the lateral expansions. The facets 

 are oblique, the right ventral to the left. They 'were continued 

 on to the lateral surfaces of the keel : ventral to each is a well- 

 developed wing of bone, preventing dislocation of the coracoids. At 

 the posterior termination of each of these is a cavity, determined 

 by Seeley to be pneumatic foramina. This may be so, but they are 

 also cavities into which the hinder point of the distal articular end 

 of the coracoids entered wdien the movements of the wings caused 

 these bones to be at their utmost posterior limit, the walls of these 

 cavities acting as stops. The articulations are pulley-joints. I 

 estimate the true length of the sternal plate to have been Qo mm., 

 and the breadth 44 mm. A restored outline, of half the natural 

 size, is given in PI. XL, fig. 5. 



1 ' Dragons of the Air ' 1901, fig. 67 & p. 175. 



