•J40 OSTEOLOGY OF AXSERES. 



succeeding one, while the following segments in the skeleton of the 

 neck are notably broad and rather long. In this region one thing is 

 sure to attract our attention, and this is the brevity of the pre- and 

 postzygapopbyses, an arrangement which has the effect of very ma- 

 terially reducing the size of the intervertebral spaces or apertures. 



In the dorsal region the vertebrae are not only locked together by 

 their close-fitting neural spines, but a very extensive system of meta- 

 pophysial and other bony spiculae render the strapping still more effi- 

 cient liie transverse processes are very wide, too, so that, notwith- 

 standing the tact that these segments are all free, the mobility enjoyed 

 by this division of the column is very much compromised. Pneuma- 

 ticity is but very imperfectly extended to the vertebra of the column, 

 especially in the cervical region ; while this is likewise true of the 

 Swans, this condition in them is very much more complete, and their 

 dorsal vertebrae are wonderfully well provided for in this particular. 



The ribs seem always to be non-pneumatic, with large anchylosed 

 unciform processes, being wide and flat in the body above the points 

 where they are attached. Glaucionetta is notorious for both of these 

 characters. 



Spatula has on one side seven ribs that connect with the sternum by 

 costal ribs: one pair behind these, where the haemapophysis fails to 

 reach that bone, and, finally, a small floating haemapophysis clinging to 

 the posterior margin of the latter. The last two pairs of vertebral ribs 

 come from the sacrum and are without unciform processes. 



This arrangement of the ribs prevails also in Anas cyanoptera, while 

 in Ulaucionetta the series leads off with two pairs of free ribs, one on 

 the sixteenth and one on the seventeenth vertebra, the following six 

 connecting with the sternum, and three pairs coming from the consol- 

 idated sacral vertebrae, making in all nine pairs of ribs to each side, the 

 last three not bearing unciform processes. 



In Olor columbianu8 the arrangement is again entirely different. Here 

 we find the series leading off with one pair of free ribs (on the twenty- 

 third vertebra), followed by nine pairs that connect with the sternum 

 by costal ribs and completed by a purely floating pair that neither joins 

 with the pelvis above nor the sternum below. This gives the Swan 

 eleven pairs of ribs. Of these the first, and the last four are without 

 unciform appendages, In those ribs where they do occur they are 

 anchylosed to them and are not notably large. The last four pairs of 

 ribs come from beneath the ilia in this Swan and curve far backward, 

 reminding us of a condition that is still more pronounced in the Loons. 

 Nor is this the only feature in Olor wherein it resembles that family, as 

 we will see further on. 



This Swan has a low median hypapophysis on each dorsal vertebra, 

 and the neural crests of these segmeuts are comparatively low, beiug 

 laced together by long spiculae, as we described them for the Ducks. 



The skeleton of the tail is much as it is in Spatula and Teals, in 



