1900. ] SHUFELDT—OSTEOLOGY OF THE WOODPECKERS. 613 
In the Tyrant Flycatcher to which I allude (1) the parial fora- 
mina of the post-acetabular region are present and large. They 
are absent in the Woodpecker. (2) In Zyrannus the descending 
process of the ischium is slender and nearly straight ; its foot does 
not codssify with the post-pubis. (3) The Tyrant Flycatcher has 
the obturate space and foramen separated bya delicate bridge of 
bone. They merge into one fenestra in the Woodpecker. (4) Zj- 
vrannus, on the ventral aspect of the basin of the pelvis, opposite 
the acetabulz, has the transverse pleur- and diapophyses thrown out 
as abutments against the ilium, upon either side, as tie-beams. 
No modification of the parts mentioned is to be seen in Sphyrap- 
icus. (5) Zyrannus has its ilio-neural canals open behind upon 
either side of the sacral crista. They are closed at those points in 
the Woodpecker. 
Before passing to the consideration of the appendicular skeleton 
it will be as well to add here that I have glanced at the ossifica- 
tions that occur in the ¢vachea of Colaptes, and it will be seen that 
both the rings and the semirings are thoroughly ossified. At the 
upper extremity we find the usual bony thyroid plate, also arytenoid 
bones of a peculiar form. Each one develops two bifurcating limbs 
behind, which gently curve toward each other, and thus enclose or 
nearly enclose a subelliptical fenestra. Their free ends articulate 
with the corresponding side of the median bone at its upper tip. 
At the syringeal end of the trachea we find an ossified pessulus, 
with the ossified semirings below it. The form of the tracheal 
rings seems to correspond with the corresponding structures as we 
find them in most all ordinary birds. 
Or THE APPENDICULAR SKELETON IN THE NORTH AMERICAN PICI. 
So far as the pectoral limb is concerned, I may say I have ex- 
amined it and compared it in some nineteen or twenty species 
of our Woodpeckers, and find that although there are some 
few distinctive characters, these appear for the most part to be 
slight, and in such a work as the present one need hardly be 
dwelt upon in detail. Pneumaticity, however, seems to differ 
among them in so far as its extent goes, for in Co/apftes I find hu- 
merus, radius and ulna all pneumatic, while in J/elanerpes tor- 
guatus only the first-mentioned bone enjoys that condition. 
Ceophleus pileatus offers us a very good average species wherein 
to study the characters presented on the part of this limb, and it 
