OSTEOLOGY OF BIRDS II 



below the femur, and all the sesamoids and ossifications pertaining 

 to the sense organs, that appear to be exempt from the condition. 

 Where its exists it- is very perfect and gives an unusual lightness to 

 the skeleton of one of these birds — forms so constantly on the 

 wing, and such masters of the faculty of flight. Notwithstanding 

 all -this, the several bones of these vulturine types are large, that is 

 in bulk and caliber, while the long bones of the wings are of more 

 than average length for the size of the species possessing them. 



SkulL Among the most of our Cathartidae the birds are nearly a 

 year old before several of the cranial sutures have become absorbed, 

 such as the frontonasal sutures, the various sutures of the lacrymal, 

 and others. These are all more than usually well obliterated, and led 

 •Huxley to say of Cathartes a. septentrion al is that 

 the " lacrymal bones are so completely anchylosed with the frontals 

 and with the broad prefrontal processes, that all traces of their 

 primitive distinctness are completely lost." [Zool. Soc. Lond. Proc. 

 1867, p. 463] In a specimen of this species of the first summer, I 

 find the great nasal bones largely overlap the frontals, being well 

 separated from each other in the middle line. The craniofacial 

 hinge is quite free, and an interesting supplementary hinge is formed 

 between the superoanterior border of either lacrymal, and the mar- 

 gin of the nasal opposite it. A small foramen is left at this point in 

 Cathartes a. septentrionalis, into which the nasal 

 glides when the superior mandible is depressed [pi. 6, fig. 9]. 

 Practically, the same condition exists in Cat h arista urubu, 

 where the nasal process becomes peglike, and really articulates in a 

 socket on the interior aspect of the lacrymal. This character is least 

 marked in the condor (Sarcorhamphus), though in our Gymnogyps 

 the nasal process of this peculiar joint is much longer, curved up- 

 ward, and glides over a greater surface on the lacrymal. 1 [See 

 pi. 2, fig. 2, 3] 



1 This mobility of the craniofacial hinge in Cathartes a. septentrion- 

 alis is responsible for a condition of separation at the pterygobasisphenoidal articula- 

 tions, for we have observed in nearly all of the dry skulls of the Cathartidae that the 

 pteryapophysial processes of. the basisphenoid never meet the facets on the pterygoids 

 that are evidently intended for their articulation. This seems to be due to a warping 

 upward of the superior mandible during the process of drying, drawing both the pala- 

 tines and with them the pterygoids away from these pteryapophyses. If we take the 

 pains, however, to dissect the head of a recently killed vulture, as the writer has done, 

 we will at once appreciate the normal state of affairs, and find that by the slightest 

 pres-ure downward of the upper bill the facets upon the pterygoids glide over the 

 pteryapophyses. We will find many of the illustrations representing them in published 

 works of other authors, with the interspace between. Our own figures illustrating pre- 

 vious memoirs do so, and Professor Huxley has done so before us. although he says of 

 Cathartes a. septentrionalis " The basipterygoid processes are large 

 and articulate with the pterygoids." [Zool. Soc. Lond. Froc. 1867. p. 440, fig. 22] 



