596 MR, P. L. SCLATER ON THE [June 27, 
no doubt whatever as to the true position of this interesting form. 
The figure represents the sternum of D. wallacii. That of D. my- 
stacea, of which also Mr. Wallace has kindly lent me a specimen, is 
nearly similar, but larger, and with the medial foramina still broader 
and more regularly oblong. 
The abnormality of the number of phalanges in the digits of 
Cypselus is well known. The medial and external digits have only 
three phalanges like the inner digit, as was first pointed out by 
Nitzsch* in 1811. This is the case, I believe, with all the species 
of Cypselus and Panyptila. Professor Baird, in his ‘ North-Ame- 
rican Birds,’ apparently misled by Streubel t, believes that in Pany- 
ptila the normal number of phalanges is present. But, as will be 
seen by the accompanying drawing (fig. 9), the same rule prevails in 
Panyptila as in Cypselus. The medial and outer digits have only 
Fig. 9. 
a SS 
Fig. 9. Left foot of Panyptila melanoleuca. 
three phalanges each like the immer. In all the other genera of 
Cypselida, as far as I have been able to ascertain, the normal rule is 
followed, the medial digit having four phalanges and the outer digit 
five. As an illustration of this form of Cypseloid foot I give a figure 
(fig. 10) of the bones of the foot of Chetura zonaris, with the pha- 
langes slightly separated as in the corresponding figure of Panyptila 
melanoleuca. 
Fig. 10. Right foot of Chetura zonaris. 
* Osteogr. Beitrage z. Nat. d. Végel, p. 104. 
T See Streubel’s remarks in the ‘Isis,’ 1848, pp. 359, 360. 
