158 Prof. H. G. Seeley on 



if it is to be regarded as scapula, while 89 and 97 may be 

 referred to Palceosaurus. 



Humerus of Thecodontosaurus. 



The specimens 95 and 96 are portions of the same bone, 

 and are the type of the humerus of Thecodontosaurus ^ which is 

 remarkable for the comparative straightness of its inner side, 

 the concavity of its external border, and the relatively small 

 proximal expansion given to the bone by the radial crest, which 

 appears to be equalled by the width of the distal end, though 

 the radial crest is imperfectly preserved. This humerus is 

 remarkably flattened, and has the proximal and distal articu- 

 lations in the same plane. The bone is exposed, so as to 

 show the superior surface at the proximal end, and the inferior 

 aspect at the distal end. The bone is much straighter, less 

 twisted, more expanded transversely at the distal end, and 

 less expanded in the radial crest than any Saurischian 

 humerus known to me ; and it differs in all these characters 

 from the other humeri found in tlie same deposit. The 

 length of the bone is 6^ inches ; the least width of the shaft, 

 Jo inch, is above the middle. The greatest width of the 

 articular part of the head of the bone exceeds an inch ; the 

 head is slightly tumid and directed upward ; while the radial 

 crest, which is not conspicuously separate from the shaft, 

 increases the width on the radial side to about 2 inches. 

 Tliere appears to have been a smooth, sharp, short margin 

 between the articular head and the compressed vertical 

 tuberosity of the outer border of the crest, which was about 

 ■^ inch long. 



The distal end widens to about ^j-^ inches. The external 

 margin is prolonged in a convex curve on to the distal 

 margin. The distal articular surface is concave from side to 

 side, and therefore saddle-shaped, seeing that it is rounded 

 from above downward. Above the articular surface the bone 

 is slightly impressed, as though by the ulna. The contours 

 of the bone at first sight approximate to those of Belodon ; 

 but the resemblance is superficial, since in that genus it is 

 the internal border of the bone which is concave and the 

 external which is nearly straight. There can be no doubt 

 that, in so far as the bone diverges from ordinary Saurischia, 

 it approaches towards existing Lizards. 



Humerus of Palseosaurus. (Figs. 8 and 9.) 



Besides the Thecodont type, there is the badly preserved 

 bone originally described as ischium, which is a large right 



