Vol. XII. 

 1913 



] Shufeldt. Osteology of Cereopsis novcs-hollandicB . 227 



distal end of the pygostyle is somewhat produced — an elongation 

 which, in Branta canadensis, is very marked. In this Goose, too, 

 there are six free caudal vertebrae, which in the case of the third, 

 fourth, and fifth have long, deflected transverse processes, and 

 thick (but b}^ no means lofty) neural spines. The fifth vertebra 

 of this series in the skeleton at hand has its transverse process on 

 the right side profoundly bifid, the bifurcations being slender and 

 spreading. Chevron bones occur as in Cereopsis. In Chen the 

 caudal vertebrae are non-pneumatic, and for size they hold an 

 intermediate place, being somewhat better developed than they 

 are in the Australian species, and not as well as they are in Branta 

 canadensis. 



The Sternum. — Dorsally, the sternum of Cereopsis is profoundly 

 and doubly concave, the two concavities merging into each other 

 in such a gradual manner as to be hardly perceptible. The trans- 

 verse line approximately dividing them may be considered to 

 pass just a little posterior to the facets on the costal borders for 

 the ultimate pair of haemapophyses. 



Similar double concavities characterize the dorsal aspects of 

 the sternum in Branta and in Chen, and doubtless in other Geese, 

 the anterior one being for the thoracic organs and the posterior 

 for a part of the abdominal ones. 



On the costal borders the articulations for the costal ribs present 

 their usual avian characters as seen in ordinary birds. They are 

 directed backwards, upwards, and outwards — very much outwards 

 in the case of Chen hyperboreus, and even more so in Branta 

 canadensis. 



Posteriorly, the xiphoidal part of the bone presents two pro- 

 found " notches," being elliptical in outline. 



The lateral xiphoidal processes thus formed are long and nearly 

 of equal width throughout, averaging about 7 mm., while the 

 median xiphoidal process is wide, its hinder border being sharp 

 and transverse. It has an average width of about 3 centimetres. 



In Branta canadensis the notches are more broadly elliptical in 

 outline ; the lateral xiphoidal processes relatively longer, with 

 their ends, posteriorly, somewhat expanded ; while the postero- 

 external angles of the mid-xiphoidal process are laterally con- 

 siderably produced. This is also the case in Chen hyperboreus 

 nivalis, but not so much so. 



Anteriorly, the border of the sternum in Cereopsis is much 

 thickened, convexed forwards, with its face in front being 

 modelled to form the articulations for the coracoids ; and when 

 these latter are articulated as in life, they do not meet mesiaUy, 

 the contracted interval being a small, rather shallow pit. This 

 is also the case in Branta ; while in Chen the coracoids come in 

 contact in the median line. 



In all these Geese the costal processes are quadrilateral in outline, 

 rather large but not lofty, while below either one of them, at the 

 outer ending of the coracoidal groove, there is another sharp 

 process developed — an osseous, broadly triangular lip, which 



