OSTEOLOGY OF BIRDS 



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ject. The posterosuperior angles of either lacrymal bone in Spatula 

 are small, free processes directed backward, but in Somateria 

 m 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 clypeata, rf, naturai 

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

 maxillopalatine. Drawn by the author 



Most clucks 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 {max) extremity of the bar is in all firmly 

 wedged in between the palatine and the dentary process of the 

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



