1890.] NATURAL SCIENCES OF PHILADELPHIA. 419 



CO-OSIFICATION OF AXIS VERTEBRA WITH THIRD CERVICAL. 

 BY EDWARD BANCROFT. 



Last summer, while in the neighborhood of Media, I found the 

 the skeleton of a young dog. It was in excellent condition, being 

 cleansed by the rain and bleached by the sun. The epiphyses on 

 the distal end of the femur were present and the sutures were well 

 defined in the skull. I secured the head together with the axis 

 and atlas vertebrae. On reaching home and carefully examining the 

 bones, my attention was first called to what seemed to be an ab- 

 normally long axis vertebra with four transverse processes. On 

 closer examination I found the supposed anomaly to consist of the 

 normal axis vertebra firmly and inseparably ossified with the third 

 cervical which may be thus described in detail : — 



Centrum normal, anterior end firmly ossified to posterior end of 

 axis; transverse processes normal, also foramen for intervertebral 

 artery ; neural arch divided, antero-posterior on the summit, divi- 

 sion passing to right of neural spine of which a mere rudiment, 

 1 mm. high, is left ; jjostzygapophyses normal ; j^rezygapophyses, 

 especially on the right side, firmly ossified to the postzygapophyses 

 of the axis. On the left side ossification is complete but not so 

 prominently marked as on the right side where the corresponding 

 zygapophyses are obliterated. 



The case is probably one of abnormal development, as an injury 

 to the animal tending to produce such effect would have resulted in 

 death. 



