apex passes far over the anterior end of the >capula. Thus a 

 piece of the clavicular end. includin- the apex, is above the 

 scapula but not bein-- m contact with it;— the actual point of 

 contact between these two bones i)eing several millimeters 

 beyond or anterior to the apex. 



The scapulae are quite long, and narrow, being gently curved 

 throughout their length in the vertical plane, the convexity 

 being along the dorsal aspect. For the most part the bone is 

 of uniform width, the head alone being somewhat thickened. 

 It offers only a moderate articular surface for the coracoid, 

 and the os furcula rests upon its upper side. 



The scapula? are especialh' slender in Colyvibiis auntiis. 

 Comparatively speaking, the coracoids are usually long and not 

 very stout ; they may, however, be only of moderate length. 

 The summit of one of these bones offers us the usual ornithic 

 characters, being peculiar only in having such a small scapular 

 process, and being rather compressed laterally. The distal end 

 of the bone is dilated and much flattened in the antero-posterior 

 direction. This expansion is carried some distance up the outer 

 side of the shaft, and, owing to the fact that the sternal end of 

 a coracoid sets so deep in its articular groove in the sternum, 

 the corresponding articular surface on the bone is carried up 

 some little distance both in front and behind, — most so upon 

 the latter aspect. 



When the bones of the shoulder-girdle in a grebe are articu- 

 lated as in life, there is quite an interval between their sternal 

 ends, mesiad. As I have said above, this interspace on the 

 sternum is concave and its convexity is coextensive with the 

 inner border of the coracoid upon either side. A wide interval 

 in the same location exists in Hcspcroniis iro-alis, the great 

 dix er of the Cretaceous epoch in America. 



The Appendicular Skeleton of the (;rehes. 



As an example of the skeleton of the pectoral limb of an adult 

 specimen of Colyvibus hollnvlli we have chosen No. 178 15 Coll. 

 U. S. Nat. Mus. In this specimen the humerus is 10.6 cms. 

 long, with nearly a straight, subcylindrical shaft, the extremities 



