OSTEOLOGY OF BIRDS 



273 



ject. The posterosuperior angles of either lacrymal bone in Spatula 

 are small, free processes directed backward, but in S o m a t e r i a 

 m o 1 1 i s s i m a they are conspicuously elongated, extending up- 

 ward, somewhat backward, and a little outward. These lacrymal 

 spines are also pretty well marked in the Surf scoter ; while in other 

 ducks they are practically absent as in the Mallard, and in Dafila. 

 The interorbital septum rarely shows any deficiencies in its bony 

 plate, the Golden-eye being one of the only forms in which I have 

 met such a condition, and in this fowl it is very small. In all 

 Anatidae the osseous pars plana seems to be aborted, simply a low, 

 bony ridge indicating where it is developed in other birds. The 

 mesethmoid is developed, however, as a strong median abutment 

 extending far forward beneath the craniofrontal region. 



Fig. 13 Right lateral view of the skull of Spatula c 1 y p e a t a , J 1 , natural 

 size. From a specimen in the author's cabinet, now in the New York State Museum 

 and used throughout this treatise where the bones of the skeleton of this species are 

 figured. I, lacrymal; Pmx, premaxillary; q, quadrate; pt, pterygoid; pi, palatine; Mxp, 

 maxillopalatine. Drawn by the author 



Most ducks have the track for the passage of the olfactory to 

 the rhinal chamber an open groove, while in Olor it may be practi- 

 cally overarched by bone. 



As already intimated in a former paragraph, Spatula, in com- 

 mon with other ducks, has a greatly lengthened sphenotic or post- 

 frontal process, while the squamosal projection would hardly at- 

 tract attention in any .of them [see fig. 13.] 



The infraorbital bar is long, nearly straight, narrow, and much 

 compressed from side to side. On its upper edge beneath the lacry- 

 mal a little papilliform elevation is usually seen. Its quadratal ex- 

 tremity is slightly tilted upward before it sinks into the pit in that 

 bone. The maxillary (mar) extremity of the bar is in all firmly 

 wedged in between the palatine and the dentary process of the 

 premaxilk, being completely fused with these bones in the adult. 



