1901.] SHUFELDT — OSTEOLOGY OF THE CUCKOOS. 13 



beneath. It barely extends beyond the broad ethmoidal wings in 

 front and ascends but little as it proceeds in that direction. In the 

 nestling it is seen to be sharp-pointed anteriorly and grooved its 

 entire length superiorly. 



The inter-orbital septum is a thin partition of bone, which always 

 possesses a considerable quadrilateral vacuity near its centre. This 

 usually merges with the foramen for the exit of the optic nerves 

 (PI. I, Fig. i), while the small foramen for the exit of the oculi- 

 motor remains distinct. 



As might be expected from what has already been said about the 

 orbit, we find its hinder wall also very broad and generally concave 

 forward. At its usual site a distinct, irregular foramen of some 

 size is found for the exit of the olfactory nerve, and this branch 

 passes forward in the living bird in a shallow channel on the inter- 

 orbital septum beneath the frontal for its entire length, where these 

 two elements are united. It leads to the inner and larger of the 

 two foramina that were described above as occurring over pars 

 plana. 



Before leaving this side view of the skull it will be as well to 

 notice the large, luniform sesamoid that occurs in the ligament that 

 passes from the quadrato-jugal to the hinder border of the articular 

 cup of the mandible. This sesamoid is present on both sides and 

 in all the skulls of Geococcyx that I have ever had the opportunity 

 of examining. 



On the superior view of the skull we are to note the form of the 

 bony laminae that partially close in the external narial openings from 

 behind ; the position of the two small circular foramina beyond the 

 cranio-facial hinge; and this fronto-lacrymal region generally. 

 From this aspect we also see the small foramina that pierce on 

 either side the orbital roofs behind. Mesially, and between these 

 latter, a shallow, longitudinal groove marks the cranial vault. Pos- 

 terior to this again we find a smooth, globular and ample parietal 

 region. The crotaphyte fossae may likewise be discerned from this 

 upper aspect and a glimpse obtained of the supra- occipital promi- 

 nence. Here, too, may also be seen the manner in which the quad- 

 rato-jugals articulate with the quadrates. 



Viewing the skull of Geococcyx from beneath, we find, anteriorly, 

 the broad, flat surface, already spoken of, which forms the lower 

 face of the superior mandible (PL I, Fig. 2). 



Following this back we come to an elongated median vacuity, 



