Shufeldt : Osteology of the Herodiones. 171 



facet is separated from 3 by a distinct valley. 6. On the inner angle 

 of the foot of the quadrate, a small circular facet, directed forwards 

 and upwards, intended for the cup on the posterior extremity of the 

 pterygoid. All these articular surfaces except the first and last, have 

 corresponding elevations or depressions for their insertion on the ar- 

 ticular end of the mandible, and I have risked the danger of being 

 considered a "dweller upon details " in order to show what an ex- 

 tensive array of facets the foot of this bone supports, and how com- 

 plicated a surface it offers to the articular extremity of the mandible. 

 I believe, that a careful study of these facets, in the Class birds, will 

 some day afford us an additional series of facts that can be used with 

 advantage in classification. 



The maxillo-palatines, the palatines, the pterygoids, and the, con- 

 dyle of the occiput, can all be seen on direct basal view, but these I 

 have reserved to describe in the two remaining aspects of the skull. 



Seen upon inferior view of the skull, the superior mandible presents 

 an unbroken horizontal surface. This is bounded on either side by 

 its sharp edges, while its middle and longitudinal line is defined by 

 a delicate and slightly elevated crest. At irregular intervals on either 

 side of the latter, minute foramina occur, from which spring branching 

 concave venations, directed forwards and outwards to the lateral 

 edges. (Fig. 2.) 



The dentary processes of this premaxillary bone are directed back- 

 wards, with pointed apices to overlap the major part of the horizontal 

 plate of each maxillary. Anteriorly, the palatines merge impercep- 

 tibly into the premaxillary, rendering it impossible in the adult 

 Heron to define the exact line of union, their inner margin also uniting 

 with each other, in a like manner, as far back as the middle point on 

 the inferior border of a maxillo-palatine. Here abruptly an interval 

 occurs between them, through which we may see the hinder half of 

 the latter bones and the lower border of the vomer. 



Still more posteriorly they become doubly carinated, the posterior 

 angle of the outer keel being bluntly pointed. At the mergence of 

 these keels behind, we find the articular heads for the pterygoids, the 

 upper surfaces of both ride the under side of the rostrum. 



Now the inner sides of the inner keels of the palatines are produced 

 forwards to merge into the vomer in a sharp point beyond, thus form- 

 ing in conjunction with this bone a long doubly carinated process, in 

 the median line, opposite the middle thirds of the palatine bodies. 



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