26 SHUFELDT — OSTEOLOGY OF THE CUCKOOS. [Jan. 4, 



ates in an elongated hypocleidium. This latter articulates when 

 the arch is in situ with the carinal angle of the sternum, in the 

 manner described in a foregoing paragraph. 



A scapula assists to form the glenoid cavity in the usual way, 

 contributing about half the surface to that humeral socket. Its 

 clavicular process reaches far forward, to make an extensive articu- 

 lation with the head of the furculum, when the bones are in the 

 position they assume in life. It also rests further forward upon the 

 scapula process of the coracoid than is usually seen among birds. 

 Sometimes we find the posterior third of the long, narrow blade of 

 this bone bent down more abruptly than in the specimen I have 

 figured in my former memoir, and its end is always rounded off, 

 rather than being truncated, as is commonly the condition in Aves. 



At the outer and back part of the shoulder-joint in the adult 

 Geococcyx occurs usually a very minute sesamoid, known as the 

 os humero scapulare, and I am led to believe that small sesamoids 

 may yet be found in other of the tendons of the pectoral extremity 

 in this region. 



Of the Appendicular Skeleton. The Pectoral Limb. — Pneuma- 

 ticity is extended only to the bone of the brachium in this limb, 

 the hollow shafts of the other long bones being charged with 

 medullary substance. 



The humeral shaft is much bowed, and in such a manner as to be 

 convex along its radial border and concave upon the opposite side, 

 which concavity is more apparent owing to the prominence of the 

 ulnar crest and the peculiar projection of the distal extremity in 

 the continuity of this curve. 



In form the shaft is nearly cylindrical and almost entirely devoid 

 of muscular lines. 



At the proximal end, a well-marked valley occurs between the 

 ulnar crest and the spindleform humeral head. The former has 

 barely any pneumatic fossa at its base, the circular foramen there 

 found being nearly flush with the general surface of the bone. On 

 the opposite aspect we find a short though prominent radial crest, 

 which makes no pretence to extend its lamelliform plate down the 

 shaft, as we often find to be the case in birds. 



The distal extremity of this bone presents for examination the 

 usual oblique and ulnar tubercle, while, as already alluded to, the 

 ulnar condyle of this end is much produced and very prominent. 



The anconal aspect immediately above the trochlea is flat and 



