1901.] SHUFELDT — OSTEOLOGY OF THE CUCKOOS. 11 



its boundaries are hard to define in the adult bird (PI. I, Fig. i). 

 This is not the case, however, in the skull of a nestling Geococcyx 

 at my hand, where the bone is easily studied. Its premaxillary 

 process is rather long and very slender, while its two remaining 

 projections are broad. Near its middle it is perforated by a small 

 foramen, which we find persists throughout life and seems to corre- 

 spond to a similar minute aperture found in the same locality in the 

 skulls of certain Kingfishers (Ceryle). All three sides of this osse- 

 ous superior mandible are more or less marked by anastomosing 

 venations, and a few perforating foramina are always seen near its 

 apex. 



A lacrymal in Geococcyx is an unusually large bone, though a 

 light one, due to its very open cancellous structure within, and its 

 being, perhaps, pneumatic besides. Superiorly, it articulates with 

 the frontal and nasal, principally with the last on the lateral aspect, 

 though it departs from it some time before reaching its lowest 

 point, where a slit-like interval is seen between the two bones. 

 Below, its broad, rounded margin is placed obliquely, its outer and 

 at the same time posterior end resting upon the upper side of the 

 maxillary, while its inner and anterior end being elevated just 

 above the superior surface of the corresponding palatine. 



The posterior aspect of the lacrymal is concave from above 

 downward, in conformity with the somewhat globular concavity of 

 the orbit, while anteriorly it is correspondingly convex in the same 

 direction. It lies in front of the broad, quadrilateral ethmoidal 

 wing which overlaps it, the two forming a very complete partition 

 between the orbit and rhinal chamber, the bone under consideration 

 closing the outer third of the space. 



The ethmoidal wing, the form of which I have just given, is 

 pierced above, immediately beneath the frontal bone, by two 

 elliptical foramina, the inner one being the larger, and both being 

 vertical. They probably transmit the olfactory nerve and vessels 

 to the rhinal space. 



This "pars plana" has, like tlie lacrymal, also a somewhat can- 

 cellous internal structure, the plate being moderately thick. Its 

 lower and outer margins are concave and smoothly rounded off. 



The expanded anterior extremity of a maxillary is immovably 

 wedged in between the nasal above and the posterior dentary 

 process of the premaxillary beneath. Its rod-like extension behind 

 forms about the anterior third of the very straight quadrato-jugal 



