OSTEOLOGY OF BIRDS 23 



limiting the symphysis posteriorly, is parabolic in outline. View- 

 ing the mandible in the Cathartidae from a lateral aspect, 

 when it has been articulated with the cranium, we observe that 

 it is bent downward from a point a little posterior to the dis- 

 tal end of the maxillary, from which point it is obliged to accom- 

 modate itself with the superior mandible. A row of foramina is 

 always present just within the sharp edge of the superior border 

 beyond, and still within these a few others are scattered about ; one 

 or two isolated, though parial, nutrient and vascular foramina are 

 found at corresponding points, along the sides of the mandibles of 

 all these vultures. 



Vertebral column. Being large boned birds generally, we find 

 that in the Cathartidae this feature is extended to the segments of 

 their spinal columns. The vertebrae are large, and all their various 

 processes well marked and strong. 



In the cervical region or division of the column we find the verte- 

 bral canals as usual, passing from vertebra to vertebra, along on 

 either side ; in each segment the tube remains throughout more or 

 less subcircular, and is closed in the ordinary manner by the para- 

 pophyses and pleurapophyses of each vertebra. The protection 

 afforded the vessels is markedly complete, for it is only in the atlas 

 and axis that we discover slight deficiencies in the lateral walls. 

 The neural canal as it passes through the vertebrae of the upper 

 half of the neck is nearly cylindrical, but as we approach the middle 

 of the neck it gradually becomes compressed from side to side, 

 and assumes the vertical ellipse, to become circular again before 

 arriving at the dorsal region. In the atlas the facet for the condyle 

 of the occiput is semilunar in outline, and the neurapophyses are 

 broad above, but as usual exhibits no sign of a neural spine. Below 

 we commonly find a well marked hypapophysis, though this feature 

 is absent in Cat h -arista urubu ; laterally we have the un- 

 closed vertebral canal of this bone, the processes receding from each 

 other as sharp spiculae. These points are still nearer together in 

 the axis, and in this segment we find a thick, quadrate, neural spine 

 occupying the center of the arch above. Below, the hypapophysis is 

 carinalike in character, traversing in the median line the entire cen- 

 trum of this bone. The odontoid process is an insignificant tip, 

 being quite broad from side to side, while the postzygapophyses are 

 tuberous lateral projections, with the facets on their under aspects 

 in the horizontal plane, looking directly downward, with the anapo- 



