OSTEOLOGY OF BIRDS 323 



n.ajority of them do not, as is the case in the eiders, Netta and 

 many oLhers. Again, it may be said that the lateral xiphoid pro- 

 cesses project beyond the middle one as in the geese; but this is 

 also the case in certain ducks, as in the eiders, Marila, and numer- 

 ous others. The form of the sternal carina in Dendrocygna is 

 more anatine than it is anserine, when compared with such a typical 

 goose as B r a n t a c a n a d e n s i.s . 



Pectoral arch. Limbs. Apart from the greater size of these 

 bones in most geese, they have the same general characters as the 

 corresponding parts of the skeleton, as they have been described 

 above for the ducks. 



In the large specimen (^) of Branta canadensis that I 

 killed at Fort Fetterman, Wyoming, in March 1880, there is a 

 big and powerful fitrcula. It is of the U-shaped pattern; slightly 

 compressed in the transverse direction ; as are its gradually pointed, 

 rather vertically deep, free clavicular heads also flattened from 

 side to side. From these ends the bone loops downward and gently 

 backward, becoming more and more subcylindrical as it passes 

 that way. At the median point of fusion below, the arch is some- 

 what thickened, but the- hypocleidium is rudimentary, and may be 

 said hardly to exist. The distal points of the superior ends are 

 very sharply pointed, but the processes on the upper borders, further 

 back, and seen in some ducks, are here hardly noticeable. These 

 latter are better seen in A n s e r a 1 b i f r o n s , where they are quite 

 distinct, antl in this species the fork of the furcular arch is consid- 

 erably broader than it is in Branta, while the mesial surface all the 

 way round is flatter. In this goose, too, the bone is pneumatic, a 

 condition that does not appear to be enjoyed by the furcula of 

 Branta canadensis. Its pneumaticity is even better marked 

 in the clavicular arch of C h e n h y p e r b o r e a nivalis, where 

 upon the external aspects of the laterally compressed clavicular 

 heads there exists, upon either side, a group of three or four large 

 foramina. Idiis goose, just named, has an os ///rr///(/ more like that 

 bone as it occurs in Branta canadensis inasnuich as the 

 form of its arch is concerned, being considerably less spreading 

 than it is in A n s e r a 1 b i f r on s . Its mesial surface is also 

 very flat, becoming locally concaved above the point of fusion, and 

 the hypocleidium is even more rudimentary than it is in Branta, 

 in fact there is really no evi Icnce of one at all. 



In Dendrocygna we find an os furcula agreeing best with that 

 bone as it occurs in A user albifrons, but better still with the 



