322 NEW YORK STATE MUSEUM 



Of moderate depth, the long triangular keel slopes gradually 

 away from before, backward. Its lower margin is of some thick 

 ness, and for the most part nearly straight, only slightly curving 

 upward, anteriorly. The carinal angle is nearly a right angle, and 

 projects hardly at all beyond the sternal body, while the anterior 

 margin of the keel above it is sharp, and posterior to this edge, 

 superiorly, a considerable thickening takes place, which adds no 

 little strength to the region. A large subquadrilateral manubrium is 

 developed, it being a transversely compressed platelet of bone, placed 

 mesially just below the capacious and united costal grooves. Again, 

 and in the median line on the true anterior brim of the sternal 

 body, is found another process. This is a low elevation, longish 

 transversely, and flat on top. A concavity exists at this site in 

 Dendrocygna, which is likewise the case in this species, where the 

 conspicuous manubrium is found in Branta. 



The entire dorsal aspect of the sternum is uniformly and quite 

 profoundly concaved, it being most profound for its anterior moiety. 

 On either side, within the anterior brim, occur numerous pneumatic 

 foramina, while in the middle line a very conspicuous pneumatic 

 fossa exists, harboring at its base many apertures, the main central 

 one of which passes directly down into the thickening of the fore- 

 part of the carina. 



These last mentioned characters hold true also for the sterna of 

 Chen and Anser, and for a less degree in Dendrocygna. In the 

 two first mentioned genera the sternal manubrium is small and 

 peglike, while the " notches " of the xiphoid are far more open 

 behind; but otherwise the sternum in either of these smaller geese 

 offers almost exactly the same characters as are presented in the 

 sternum of Branta canadensis. Dendrocygna, as I have 

 already said, lacks a manubrium on its sternum, while the more 

 acute carinal angle of its keel projects further forward than it does 

 in any of the true geese. In it, too, the muscular line of the pectoral 

 is different, for it is very distinct for its entire course. Posteriorly, 

 it keeps quite clear of the mesial edge of the xiphoidal notch, and 

 curving inward it comes to the keel before the latter begins to 

 merge with the surface of the mid xiphoidal projection, behind. 

 Seen from in front, these two muscular lines have the appearance 

 of a long loop on the ventral aspect of the bone. 



I see quite as much, if not more, duck in this sternum of Den- 

 drocygna autumnalis, than I do goose. Some ducks, to 

 be sure, possess a manubrium, as, for example, the teals, but the 





