156 MEMOIRS OF THE CARNEGIE MUSEUM 



The neural spine, feebly developed in the third vertebra, becomes a prominent 

 character of the fourth, where it occupies the posterior moiety of the bone, as a con- 

 spicuous blade-like crest, with rounded superior margin. In the fifth, sixth, and 

 seventh this character disappears ; in the eighth it is feebly present ; in the ninth it 

 is a roughened tubercle, entirely vanishing again in the tenth to the fifteenth 

 inclusive. In the remainder of the series, back as far as the pelvis, it is large 

 and of an oblong form, with thickened superior border. Throughout the dor- 

 sal vertebrae, ossified tendons of great length are coossified with this spine, pro- 

 jecting backward in the leading dorsals, and both backward and forward in the 

 ultimate ones. 



A low, sharp, haemal spine occurs on the ninth vertebra ; it being at the anterior 

 part of the bone, on the parapophysial bridge that closes in the passage for the 

 carotids. It is still better developed on the tenth ; where sharp lateral ridges begin 

 to show, one upon either side of it. All these processes are very pronounced in the 

 thirteenth and fourteenth, while in the fifteenth their entire character is changed. 

 In it the lateral ridges almost entirely disappear, and an enormous, quadrate haemal 

 spine is thrown down from nearly the entire length of the centrum. In the sixteenth 

 it is not quite so large, and its hinder angle is produced backwards. A remarkable 

 change is seen in the seventeenth vertebra, where the ventral aspect of the centrum 

 is very much broadened, quite flat, and the little hook-like, laterally-compressed 

 hsemal spine occupies a mid-position on the posterior border. In the eighteenth, 

 ninteenth and twentieth the process is practically absent, and the great breadth of 

 the centrum gradually narrows again, as its lateral margins are deflected. This form 

 sees its extreme in the twenty-first vertebra, where the centrum is markedly com- 

 pressed from side to side, and the aforesaid lateral margins are, ventrally, converted 

 into a double haemal spine. 



In the twenty-second and twenty-third the spine is single, and the transverse 

 compression of the centra is most apparent, being present in a marked degree. 



Anapophysial ridges are more or less conspicuously developed in the ninth to 

 the fourteenth vertebrae, inclusive, and in the dorsal series proper, are long and 

 broad, and, as said above, are 'provided with fringe-like metapophyses frequently of 

 considerable length. 



In the first eight cervicals, the anterior articular facets are placed laterally upon 

 either side of the neural canal, and their surfaces face forwards and towards the 

 median plane. In the ninth vertebra these facets are, as it were, rotated backwards, 

 so as to be above the neural canal, and face towards the median plane, and very 

 slightly dorsad. 



