SHUFELDT : OSTEOLOGY OF THE STEGANOPODES 191 



and behind by a low, smooth ridge which arches between its lateral boundaries. 

 The foramen magnum cannot be seen on a direct vertical view of the base of the 

 skull (PL XXVII., Figs. 35 and 36). 



The occipital condyle is rather large, ellipsoidal in form, and placed transversely, 

 while the outline of the foramen is also a broad ellipse, but with its long axis placed 

 just the other way. The plane passing through its periphery makes an angle with 

 the plane of the basis cranii of about sixty degrees. 



Regarding this skull from a superior aspect we are to note the small, subcircular 

 openings to the nostrils, situated a little beyond the irregular line marking the 

 cranio-facial hinge (PI. XXVII., Fig. 40). 



Their centers are about 2 mm. apart, and each one is situated at the posterior 

 end of a groove. These grooves extend the entire length of the superior mandible, 

 passing out on either side of the hook at its anterior extremity. At first each is 

 rather on the lateral aspect of the bone, but beyond the posterior half they gradu- 

 ally converge and get on top, to include between them the prominent convex cul- 

 men. Just before reaching the hook, however, the included surface becomes Mat 

 and depressed, when the lines terminate, as pointed out above. 



The top of the skull in this Pelican is very flat for the frontal region, being 

 simply curved downward at the outer borders. As we proceed backward to the 

 parietal region, however, it gradually becomes more convex and dome-like, though 

 still retaining its absolutely smooth and polished character. This latter may also 

 be seen from a posterior aspect, and below it the high, arching, and equally smooth 

 occipital area. This latter extends down on either side over the enormous mas- 

 toidal elevations of this bird. We also notice that from this view we may see 

 directly into the foramen magnum ; the entire pterygoids are in sight, and the quad- 

 rates come down far below the basi-cranial plane. 



The mandible from the skeleton of this Pelican is represented by a long, narrow 

 loop of bone, which is strikingly devoid of prominent characters. Its symphysis is 

 very short and decurved, being slightly excavated on its superior aspect behind (PL 

 XXVII., Fig. 41). 



The upper and lower margins of either ramus are rounded for their entire length, 

 while the sides included between them become gradually narrower as we proceed in 

 the direction of the symphysis. These are smooth both internally and externally 

 and both concave in the vertical direction. 



Rather more than the posterior moiety of each ramus is hollow for the admis- 

 sion of air, and each presents two foramina, which seem to be intended for that pur- 

 pose. One of these is on the inner and upper aspect of the ramal shaft, just beyond 



