BY C. D. GILLIES AKD B. B. TAYLOR. Ib7 



On account of the number of abnormalities present 

 it was thought advisable to consider the individual com- 

 ponents of the column separately. 



Atlas. Ventrallj' the vertebra conformed to the 

 typical condition, but from the dorsal surface it was abnormal 

 in regard to the position of the neural crest, which Avas 

 situated to the left of the longitudinal mid-line of the lamina, 

 thus causing the left slope of the latter to be much steeper 

 than the right. In addition, the left post- zygapophysis was 

 rudimentary and the posterior border of the lamina ran 

 antero-laterally to the left. 



Second vertebra. The neural crest was similarly 

 situated to that of the atlas, and anteriorlj^ its spine boie 

 a well-developed articular surface, which came into relation- 

 ship with the atlas. The pre-zygapoph3'ses weie unequal 

 in size, the right being the larger. From the ventral sur- 

 face the posterior portion of the centrum was displaced to 

 the right, and the diajiophyses cut the horizontal at an 

 angle of about 25°, the process on the left sloping anter- 

 iorly and that on the right posteriorly. The latter diapop- 

 h3'sis came into close relationship with the corresponding 

 transverse process of the third vertebra. 



Third vertebra. The malformation of this was con- 

 siderable as it Avas composed of distinct light and left 

 <livisions, each contributing to the formation of the centrum 

 and the neural arch. Examined dorsally, the neural crest 

 was borne bj^ the right component, the diapophysis of which 

 formed a greater angle ^^•ith the horizontal than the corres- 

 ponding process on the left, and furthermore was dilated 

 into a rectangular expansion. This transverse process was 

 broader and shorter than that on the left, which was typical. 

 From the ventral surface the two portions of the centrum 

 were separated by an oblique fissure running antero-laterally 

 to the left. The most remarkable feature of this region 

 was the articulation with the second vertebra, the centrum 

 of which came into relationship with only the right compon- 

 ent. 



Fourth vertebra. The left portion of this vertebra, 

 viewed dorsally, was strangely modified causing a reduction 

 of the neural arch on the left. The right post-zygapophysis 



