OSTEOLOGY OF BIRDS 



33 



S a r c o r h a m p h U s gryphus has three sacral ribs upon 

 either side; the first two pair support epipleural appendages and 

 articulate with the sternum through the agency of well developed 

 sternal ribs. The last pair are devoid of unciform projections, and 

 their sternal ribs in turn articulate by their distal extremities and a 

 small portion of their distal and anterior margins along the posterior 

 borders of the sternal ribs in front of them, their points coming 

 within about a centimeter of the costal border of the sternal body on 

 either side. Gymnogyps will probably be found to possess the 

 same arrangement of its sacral ribs as has just, been described here 

 as obtaining in the Condor. Gyparchus possesses two pairs of these 

 ribs, both articulating with the sternum by sternal ribs that are the 

 largest and longest of the series. The first pair have unciform pro- 

 cesses. Sometimes in this species an additional rudimentary pair 

 are found to exist, and belong to the next vertebra beyond, but all 

 the distinctive characters of the upper part of a rib have been ab- 

 sorbed by the under surface of the ilium, so that this pair almost 

 has the appearance of being offshoots from the ossa innominate. 



In C a t h a r t e s a . s e p t e n t r i o n a 1 i s we discover two pairs 

 the first connecting with perfect sternal ribs coming from the ster- 

 num below, and support epipleural appendages ; the last are without 

 them, and otherwise behave as we described the ultimate pair in 

 Sarcorhamphus. Passing to Catharista, we find the same arrange- 

 ment present asinCathartes a. septentrionalis, but 

 in addition a pair of rather long styliform, rudimentary ones are 

 found, with their capitula, tubercula, and 'their necks aborted as in 

 Gyparchus, though evidently belonging originally to the next verte- 

 bra in order. So then, among the Cathartidae the variations observ- 

 able among the plans for the sacral ribs resolve themselves into the 

 following four classes : as to the number of pairs; as to the presence 

 or absence of rudimentary ribs; as to the method of articulation of 

 the last pair of sternal ribs, i. e. whether these descend to the ster- 

 num or not ; and finally, as to the arrangement of the unciform ap- 

 pendages. 



Turning to the vultures of the Old World, we find that Neo- 

 phron percnopterus has a free pair of sternal ribs that 

 articulate with the sternum, but no sacral ribs that join them from 

 above. Similar ribs are found in V u 1 1 u r c i n e r e a and Gyps 

 bengalensis, " but they do not even reach the sternum " 

 [Lucas]. The authority just quoted further states that in Oto- 

 g y p s calvu-s "a very small floating rib is attached throughout 



