5o6 SHUFELDT. [Vol. XVII. 



With respect to the pneumaticity of the long bones of the 

 Hmbs of the pigeons we have had under consideration in this 

 chapter, I would say the humerus is the only bone of the pec- 

 toral extremity that enjoys this condition, and the air is 

 admitted to the shaft of it in all our ColimibidcB, — so far as 

 my observation goes. 



Th.&fe7mir I am more doubtful about, for in some species it 

 has the appearance of being pneumatic, while in others it is 

 most assuredly not so. Melopelia leucoptera seems to belong 

 to the first-mentioned class, while the bone is undoubtedly 

 non-pneumatic in the Ground and Inca doves. 



Priticipal Osteological Characters of the United States Cohitnbidce. 



1 . Completely schizognathous birds, with elongated narial apertures in the 



skull, which are not separated by an osseous septum nasi. 



2. A large lacrymal present which fuses extensively with the pars plana, 



thus forming an unbroken plate. 



3. Large vacuities in the anterior wall of the brain-case, the lower one of 



which merges with a big one in the interorbital septum. 



4. Zygoma very slender. 



5. Basipterygoid processes present which may (in all save Ectopistes f) 



or may not articulate with the short pterygoids — the latter not in 

 contact in the middle line anteriorl)-. 



6. Palatines very slender, with their laminae somewhat reduced, and with 



their postero-external angles completely rounded off. 



7. Maxillo-palatines antero-posteriorly elongated, internally spongy, and 



fused with the prepalatines, the maxillary, and the premaxillary. 



8. The premaxillary process of either nasal bone carried far forwards, 



beneath the osseous culmen. 



9. Sphenoidal rostrum sharp in front, thick and rounded behind. 



10. Vomer may or may not be present (.?). Huxley figures Columba palwn- 



bjis, and says, "The vomer is very slender" {P. Z. S., 1867, p. 434). 

 Parker says the pigeons are without a vomer. 



1 1 . Quadrates typically ornithic, and with two transversely disposed facets 



for articulation with mandible. 



12. Mandible V-shaped, its symphysis short and feeble ; articulatory ends 



transversely truncated posteriorly, from above downwards and for- 

 wards ; ramal vacuity may {Ectopistes) or may not {Starncenas) be 

 present. 



13. Eighteen {Ectopistes') ox nineteen (6'/«r«Q?«rti') vertebra in the spinal 



column between the skull and pelvis. Three leading dorsal verte- 

 brae fuse together to form one bone {Ectopistes^, and with it may 



