16 SHUFELDT — OSTEOLOGY OF THE CUCKOOS. [Jan. 4, 



and Can'ama, as well as in some Laridse and Alcidae, so that its 

 presence is obviously of no particular taxonomic value." {Coll. 

 Scientif. Mem., p. 415.) 



A pterygoid is a nearly straight and slender bone, and shows not 

 the slightest evidence of the development on its shaft of an apophy- 

 sis, and indeed there is no necessity for such, as the basipterygoidal 

 processes are entirely absent in this bird ; and the pterygoids when 

 in situ occupy a lower plane than the basitemporal region, as well 

 as being at seme distance in front of it. 



These bones articulate with each other anteriorly and with the 

 opposed palatines ; from this point they diverge at an angle of 

 about 85 °, each to meet the usual facet upon the corresponding 

 quadrate at the base of the inner and smaller condyle on that bone. 



The basi-temporal region is elevated above the prominent and 

 raised boundaries of the auricular apertures ; it is narrow and smooth 

 and lies for the most part in the horizontal plane. In front, it 

 presents for our examination a thin tip of bone, arching over the 

 common aperture of the Eustachian tubes. 



Beyond this it contracts to form the sphenoidal rostrum, a con- 

 siderable portion of which is unoccupied before we reach the ptery- 

 goidal heads. This allows these bones not a little backward play 

 in the recent specimen, an action which is quite possible from the 

 more than ordinary mobility enjoyed on the part of the cranio- 

 facial hinge. 



Either external auricular couch is a capacious fossa, well denned 

 by a raised and bounding thin wall of bone, with its free edge 

 curled in all round. At the base of either of these fossae we see 

 strong osseous trabecular, converging to a point near the centre to 

 support the double concave facet for the mastoidal head of the 

 quadrate. These stand between the Eustachian entrance and the 

 passage to the middle ear. 



If the plane of the basis cranii be produced posteriorly, and the 

 plane of the occiput and foramen magnum extended to meet it, we 

 find the latter makes an angle with the first-mentioned plane of 

 about 48 , while the long axis of the fairly well-developed supra- 

 occipital prominence would be perpendicular to it. In form the 

 foramen magnum is broadly cordate with its apex above ; the occi- 

 pital condyle at its lower margin is small, sessile and hemispherical 

 in outline, being so placed as to encroach upon the foraminal peri- 

 phery for about one-third of the condylar arc. 



