170 Annals of the Carnegie Museum. 



both young and adult, would be required, for me to examine and de- 

 cide upon such a point. 



The quadrate of the Blue Heron is a large and massive bone, and 

 indeed, such is its character in all of the ArdincB so far examined by 

 me. Its head presents for our examination two distinct and elongated 

 articular facets, separated by an abrupt and squarish notch. These 

 facets occupy the inner and outer borders of the head of the bone, 

 with their long axes parallel to the long axis of the skull ; the outer 

 one, which at the same time is slightly the larger, is in advance of the 

 inner, a circumstance which makes it rather appear that this end of 

 the quadrate was obliquely twisted. Anteriorly, the bone develops a 

 broad lamelliform orbital process, which is flattened behind and con- 

 vex forwards in front, and gently curved throughout, to the same de- 

 gree as the posterior wall of the orbit behind it, though it does not 

 touch the latter. 



The apex of this orbital process of the quadrate is nicely rounded 

 off, and the anterior surface immediately below its border looks almost 

 directly forwards, a difficult thing to show in a drawing. (Figs. 2 and 3. ) 

 Posteriorly, the shaft of the quadrate is pierced by a large pneu- 

 matic foramen, sufficiently large to permit one to see the trabeculse 

 spanning its hollow interior, from wall to wall. The massive foot of this 

 bone presents for examination six articular facets. They are the follow- 

 ing : I. xA facet upon the lateral aspect the usual cup for the ball and 

 socket joint with the quadrato-jugal. 2. On the extreme outer side of 

 the inferior surface, a sub-elliptical facet, separated from the remaining 

 four by a deep valley. This facet is the largest of the group ; its 

 anterior end is innermost, and it is intended to articulate with a cor- 

 responding surface on the mandible. 3. A smaller elliptical facet, 

 with its axis parallel to the last, situated immediately across the valley 

 referred to above. This is the lowest facet of the group, the skull 

 being held with its superior surface, upwards. From the outer side of 

 this facet a concave articular surface is carried down, to extend partially 

 across the anterior margin of the intervening valley. 4. A posterior 

 elliptical and smaller facet, higher up on the bone than either 2 or 3, , 

 being directed somewhat backwards. A concave, narrow, articular 

 isthmus connects this facet with No. 2, occupying the posterior margin 

 of the intervening valley. 5. A large circular facet occupying the 

 surface of the inner aspect of the foot of the quadrate, directed down- 

 wards, backwards and inwards, the skull being held as above. This 



