54 THE ROYAL SOCIETY OF CANADA 



The Post-Sacral Region 



The slab of rock containing the bones immediately posterior to 

 the sacrum has been partly prepared. Sixteen vertebrae are exposed 

 showing a length of 4 ft. \]/2 in. The neural spine of the anterior is 

 about 1 ft. 1 in. long, and that of the twelfth is 9 inches long. 



Ossified muscle-tendons are developed in great perfection; of 

 these there seems to be three distinct sets. The first set is closely 

 applied to the sides of the neural spines; the tendons are inclined 

 slightly upwards posteriorly, and stretch over 10 spines, reaching a 

 length of 2 ft. 3 in. The second set underlies the first; the tendons 

 pass backwards and downwards and occupy the space of from 3 to 5 

 spines. The third set has not been so well worked out as yet; the 

 tendons are more slender and less regular; they seem to pass from the 

 neural spines backwards to the diapophyses. It is confidently expected 

 that a wonderful series of ossified tendons will be revealed when the 

 main portion of the vertebral column is worked out. 



The anterior chevrons are about one foot long. Impressions of 

 skin are common and all show a uniformly tuberculated pattern, 

 not differing from those observed in other parts of the specimen.^ 



The Pectoral Girdle and Fore Limb 



Sufficient work has been done to show that both sides of the 

 girdle and both fore limbs are completely preserved, including two 

 sternal bones. The left side has been prepared and the bones com- 

 pletely removed from the matrix. 



The scapula (Figs. 2 and 3) is broad in the blade, only slightly 

 constricted in the shaft, and rather massive at the articular end; it 

 does not differ markedly from the scapulae of other trachodonts. 

 The external face is flat posteriorly and not so decurved as in Marsh's 

 figure of Claosaurus. The ridge posterior to the articular surface is 

 very prominent with a deep cavity below. The inner face is flat in 

 the blade portion and slightly concave anteriorly. The articular 

 face shows two distinct concavities, one for the coracoid and the 

 other forming part of the glenoid cavity. The figures and the follow- 

 ing measurements will sufficiently define this bone : 



^ Later investigations have shown that the tuberculation of the skin is not 

 uniform. 



