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NEW YORK STATE MUSEUM 



me strongly of the sternum of certain loons. The manubrium is 

 very minute, and the carina, although agreeing in form with the 

 keel of the sternum of Spatula, does not, posteriorly, reach to the 

 end of the sternal body, due to the fact that the mid xiphoid 

 processes are further extended behind by a rounded shield of bone 

 of a pattern not at all unlike what we see in Gavia. The lateral 

 xiphoid processes are somewhat curved inward and produced 

 backward, passing, on either side, conspicuous processes on the 

 mid xiphoid prolongation, that in other ducks are the real postero- 



Fig. 27 Sternum of So materia dresseri; pectoral aspect [U. S. Nat. Mus. 

 Osteo. Dep't, spec. 16989]. Natural size. By the author 



external angles of the latter. The " notches " (one on either side) 

 are large and subelliptical in form; and there are seven haemapo- 

 physial facets upon either costal border. 



Polysticia stelleri has a like number, and in the sternum 

 of this species we find the manubrium very small; the carinal angle 

 less acute, and consequently the keel not so far extended forward; 

 the costal processes having spinelike projections directed to the 

 front from their superoanterior angles ; and, finally, the mid and 



