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NEW YORK STATE MUSEUM 



bar bat us) [Collec. U. S. Nat. Mus. no. 17834]. A number of 

 figures of the bones of the skeleton of these two species are to 

 be found in my plates. 



Almost the entire skeleton of Helotarsus is pneumatic, and al- 

 though osteologically the bird is a true eagle, it differs, among other 

 things from such a form as Haliaetus leucocephalus, 

 in having large foramina, one upon either side, in its sternum; in 

 having in the skull, the external narial apertures largely rilled in 

 with bone ; while in the pelvis, the anterior parts of the ilia are not 

 nearly so much spread out laterally. The bones of the shoulder 

 girdle possess the same general morphology in the two species, 

 Helotarsus differing principally in its having the conspicuous pneu- 

 matic openings ; especially in the large foramen near the head of 

 either scapula. The long bones of the limbs are much alike in 

 Helotarsus and the White-headed eagle. 



Gypaetus foarbatus possesses a skeleton that offers many 

 points of interest to study. Many of its principal bones are illus- 

 trated in my plates, especially the skull, sternum, and pelvis. Al- 

 though pneumatic, many of the bones of the skeleton of the Lam- 

 mergeyer are solid and heavy. Osteologically, the bird is of very 

 powerful frame. The furcula is of the wide U-pattern, and its free 

 ends superiorly do not articulate with the scapula upon either side ; 

 an interval of five millimeters existing between them when the 

 bones of the arch are naturally articulated. The body of the ster- 

 num is short, and the keel to this bone quite shallow. In the pelvis 

 the postpubic styles are entire, and, upon superior aspect, it will be 

 seen that very complete fusion exists among the ossa innominata 

 and the pelvic sacrum. 



Considered osteologically, the Lammergeyer is an Old World 

 vulture (built essentially upon the eagle model, as Gyps f ulvus 

 is an eagle-vulture, built essentially upon the Cathartine type. A 

 comparison of the skulls shown in figures 2 and 3 of plate 2, with 

 figure 4 of plate 3, and figure 7 of plate 5, with figure 12 of plate 7 

 will demonstrate in a general way what is intended to be conveyed 

 upon this point. Gypogeranus serpentarius [pi. 1, 

 fig. 1] also stands in here, for it possesses both eagle and vulture 

 in the characters of its skeleton ; the sternum being short, with 

 a shallow keel, and (usually) no xiphoidal foramina. The post- 

 pubic styles are entire, as is the case in vulturine birds generally, 

 while, as we are well aware, the most extraordinary departure the 

 Secretary-birds make from their relatives in the suborder to which 



