BY PROFESSOR STEPHENS, M.A., F.G.S. 1187 



The size of the pits increases regularly from this centre to the 

 periphery. The lateral plates or clavicles are irregularly triangular 

 in form and largely overlap the anterior portion of the inter- 

 clavicle ; although apparently not meeting in the median line. 

 The external angle is the thickest portion of the lateral plate, and 

 from this point there radiates a sculpture very similar to that of 

 the median plate. The hone is sharply flexed at the external 

 angle, beyond which it is produced into a slender process which is 

 in apposition with a slender and but imperfectly preserved bone, 

 termed by Prof. Gaudiy the supra clavicle (sus-claviculaire). 

 Fragments of other bones are seen lying in a deeper plane at the 

 posterior border of the thoracic shield which doubtless represented 

 other elements of the shoulder girdle, but they are too imperfectly 

 preserved to admit of determination ; although one of them may 

 very probably correspond to the coracoid." The figures which 

 Lydekker gives of the thoracic plates correspond exactly, except 

 in the greater maturity of their development, and therefore in their 

 size, excepting also the doubtful restoration of the medial, with the 

 characters of our specimen. But in both figures (Plate 3 and 4), 

 the ventral aspect is represented, showing the medial overlapped by 

 the laterals, instead of the laterals being overlapped, as in the 

 dorsal aspect, and in this specimen, by the medial. I may observe 

 that in plate 4 the figure is upside down, the anterior portion 

 being turned towards the bottom of the page.] 



The sixteenth vertebra, counting from the posterior edge of the 

 medial plate carries on the right hand side of it a bone in the 

 position of the proper rib, and differing from the other ribs, at 

 least at the proximal end, only in size, having the head nearly 

 twice as broad as theirs. The shaft appears to expand towards 

 the distal extremity, but is imperfect. Of the corresponding bone 

 on the left side only the head is preserved. 



The next vertebra is more closely approached on both sides by 

 a pair of bones, which are very imperfect, and are smaller 

 than the preceding pair. It is quite possible that a little clearing 

 of the matrix might give us more information here, at least on 

 the right hand side. But I religiously refrain from tampering with 

 the goods of which I am only ' bailee.' 



