314 
DR. R. W. SHUFELDt’S MORPHOLOGICAL 
Species. 
No. of ver- 
tebrse before 
reaching the 
sacrum. 
First free 
pair of ribs 
occur on 
the 
No. of ver- 
tebrse in 
sacrum of 
pelvis. 
No. of ver- 
tebrse in 
coccygeal 
division, in- 
cluding 
pygostyle. 
Ampelis cedrorum 
18 
12th. 
10 
9 
Hesperociclila ncevia 
18 
12th. 
12 
7 
Tyrannus verticalis 
19 
13th. 
10 
8 
Otocoris alpestris 
18 
13th. 
11 
7 
Of this kind of data I think the greatest reliance is to be 
placed in the number of free vertebrae in the cervical + the 
dorsal region, as shown in the first column, far more than that 
shown in the three remaining columns. If we take immature 
birds, however, chosen just at that point in their development 
when we can count with certainty exactly how many of these 
segments will enter into the pelvic sacrum, and exactly how 
many will be appropriated by the pygostyle, then the total count 
of all the vertebrse in the column, irrespective of its divisions, 
will be of value. 
24. In both Avipelis and Hesperociclila five pairs of dorsal ribs 
possess costal ribs that meet the sternum, and each of these 
birds have a pair of ribs that spring from the first sacral ver- 
tebra, which articulate below with a pair of “ floating ” costal 
ribs. This condition also obtains in my specimen of Tyrannus 
verticalis , but in this species there are only four pairs of 
costal ribs that articulate with the sternum. These “ sacral 
ribs ” are without epipleural appendages, though these processes 
are found freely articulated at their usual sites upon all of the 
true vertebral ribs in the several birds just alluded to. 
25. It has been always a matter of some surprise to me that 
the pelvis of a bird has not had that importance attached to it 
among skeletal characters which has been so universally awarded 
to the sternum. In many respects its form in some species is far 
more distinctive of the bird to which it belongs than the ster- 
num can be, and is consequently more reliable. Tor instance, the 
sternum of Passerine birds varies but very little throughout the 
group, and in many cases it would be very difficult to designate 
the species by simply examiuing the sternum alone ; moreover the 
