360 Shufeldt, Osteology of the Passenger Pigeon. [j^^y 



the margins of the large orbits are cultrate, while the posterior 

 processes at lateral aspect of the brain-case, as the post-frontal and 

 squamosal, are much reduced. Basis cranii is horizontally disposed, 

 and the brain-case is of good capacity, while the rather high 

 foramen magnuvi is of cordate outline, with the very small occipital 

 condyle minutely notched posteriorly. 



Large vacuities occur in the interorbital septum, as shown in Fig. 1 

 of the Plate, where, too, we are to observe the bulky pars plana, 

 and the elongate, narrow, though capacious, external narial aper- 

 ture. 



The superior mandible is nearly straight, being gently decurved 

 at its apex, and, as a whole, making an open angle with the slender, 

 straight, zygomatic or infraorbital bar. A lacrymal, which is of 

 good size, completely fuses with the pars plana in the adult. 



A vomer appears to be absent, while the quadrates, the small 

 pterygoids and the palatine structures are all as we find them in this 

 group of birds generally — that is, in the typical and smaller 

 varieties of the wild pigeons. 



The mandible is of an acute V-shaped pattern and slender in its 

 proportions, with a weak and short symphysis. 



As to the hyoidean arches, they are as we find them in most pi- 

 geons, and not unlike those structures in certain of the smaller 

 species of the tetraonine types, being slender and formed as shown 

 in Fig. 3 of the Plate. As usual, the glosso-hyal is performed 

 entirely in cartilage. 



In Figure 2 the united sclerotal plates of an eye are shown ; there 

 are some 13 or 14 in either circlet, and they are shaped as we find 

 them in other Columboe. 



The Trunk Skeleton: — Between the skull and the pelvis Ecto- 

 pistes has eighteen vertebrae, while fourteen unite most solidly 

 together to form the pelvic sacrum; finally, there are six in the 

 caudal division of the vertebral column, and all beyond these last 

 go to form the large, subtriangular pygostyle. 



As in many fowls, the three leading dorsal vertebrse fuse to form 

 one bone, and the ribs they support are connected with the sternum 

 by costal ribs or hsemapophyses. This is also the case with the 

 pair of ribs belonging to the last dorsal vertebra, the remaining 

 ones being disposed as shown in Fig. 1 of the Plate. 



