1891.] SAXJROGNATHISM OF THE PICI. 127 



They may come to the posterior margin of the right external narial 

 aperture. They may hardly come up on the cranium at all. 

 Whenever theydo, the cranium is usually externally furrowed to 

 receive them. 



22. Sclerotal plates of the eye commonly fuse completely together 

 around their external periphery and towards the centre. 



23. " Double ' infrastapedial ' and ossified stylohyal " (Parker). 



24. Rings, semirings, and other parts of the trachea ossify, 



25. There are 19 free vertebrae between the skull and pelvis : the 

 vertebrarterial canals pierce the atlas, and in some species the axis ; 

 the atlautal cup is perforate ; there are no parial parapophyses ; the 

 carotid canal may or may not be entirely closed in by bone ; where 

 they are present the neural and haemal spines are usually very large. 



There are three pairs of cervical ribs, five pairs of dorsal ribs, and 

 one pair of sacral ribs. The hsemapophyses of the latter do not reach 

 the sternum. In some species the first pair of costal ribs are very 

 robust, as are the last pair of cervical ones. There are five or 

 usually six tail-vertebrse (free), with an enormous pygostyle. Most 

 of these parts are highly pneumatic. 



26. The sternum is 2-uotched on either side of the carina ; the 

 manubrium is either slightly or very much bifurcated ; the costal 

 processes are long and pointed, and the keel is usually rather 

 shallow, projecting forwards and carried up under the manubrial 

 process. The sternum is usually completely pneumatic. 



27. In the pelvis we find the ilia gradually diverging from the 

 sacral crista as they pass forwards. Parial interdiapophysial fora- 

 mina are either very minute or entirely absent. Ischial notch on the 

 posterior margin of the bone long, rounded, and shallow. Acetabulse 

 large, and bases completely absorbed. Sides of pelvis usually very 

 deep. Postpubis slender, extends beyond ischium, the foot of which 

 latter may or may not fuse with it. Obturator space large, and 

 may or may not merge with the obturator foramen. Three of the 

 vertebrae of the sacrum anteriorly throw out their processes against 

 the ventral iliac walls. The pleurapophysial and transverse processes 

 of the sacral vertebrae opposite the acetabulae are not modified and 

 lengthened so as to act as braces at the points in question. The 

 pelvis is commonly completely pneumatic. 



28. Bones of the shoulder-girdle pneumatic, with the excep- 

 tion (sometimes) of the furcula. This latter is of the U-shaped 

 pattern, without hypocleidium, large, flat scapulo-coracoid ends 

 (which originate from separate ossific centres in the young), and with 

 laterally compressed limbs. Posterior end of scapula more or less 

 modified to be bent or to curl outwards, giving the bone a very 

 unique form. Coracoids long, not very stout, and with the anterior 

 end more or less laterally compressed. 



29. An OS humero-scapulare present at either shoulder-joint ; 

 functional, and has much the same shape as the ossicle has in the 

 Passeres, 



30. Either the humerus alone, or it together with the long bones of 

 the antibrachium, may be pneumatic. As nalJ sesamoid is found at 



