594 MR. P. L. SCLATER ON THE [June 27, 
which is so well developed in all the true Passeres. The two rami 
of the furcula are completely joined at its apex, which is situated at 
some distance from the anterior margin of the keel, and at about 
half the height of the keel from its base. 
Figs. 1 and 2. Sternum of Cypselus apus. 
Such are some of the more noticeable points in the formation of 
the sternum of Cypselus. They have been so frequently described 
that I should not have alluded to them unless I had wished to call 
attention to the fact that all the other genera of the same family 
present a nearly similar form of sternum. In Chetura (figs. 3 & 4) 
Fig. 3. Fig. 4. 
Figs. 3 and 4. Sternum of Chetura zonaris. 
the general characters are nearly the same, although the whole ster- 
num is broader in proportion and less elongated, and the anterior 
point or apex of the keel is not carried so far forward. The body 
of the sternum is also incompletely ossified, presenting traces of two 
