No. 445-] OSTEOLLkiV ()/■ P )-(.;(^POJ)KS. 



23 



of which are but moderately enlar<;e(l. At the i)r().\iinal end 

 the radial crest is seen to be much rcchiced. and the e\ca\ation 

 overshadowed by the low ulnar crest which is unusually shallow, 

 with no evidences of pneumatic orifices. The artii ular suriaec 

 of the humeral head has the ordinary avian charactci-. Dislally. 

 the oblique and ulnar tubercles are i)ronunent and olTcr consid 

 erable articular surface for the antibrachial bones. Tlu' ulna is 

 10.2 cm. in len-th. and considerably c-omprcsscd subtrans- 

 versely ; the Ion-, slender radius when articulated, /// .svV//. with 

 it, is in contact with its shaft for its distal nioicty, thus much 

 reducing the "interosseous space, " which, in reality, only exists 

 proximally. Manus has a total length <.f S.;, cms,, and the two 

 usual free carpals arc iMesent in the wrist. ( "arix^metacarpus is 

 peculiar in being so comparati\ elv long and slender, and for 

 having the index and medius metacari)als so close together, and 

 so nearly parallel. The phalangeal digits are long and slim, and 

 I fail to f^nd any - claws" upon the distal extremities of any of 

 them. The proximal phalanx of the index digit is also el.)ngated 

 and remarkably narrow ; the expanded portion and digital shaft 

 being indistinguishably merged with each other. 



The skeleton of the wing in Podilyvibus podu cps has the same 

 essential characters as in the wings of the long-billed grebes. 



lengths and calibres with the bones of the ])elvic limb, in any 



AUogetherone of the mo.st beautiful adai>tive structures is the 

 pelvic limb of a grebe. When properly articulated, the short 

 femur has its long axis directed from the acetabular center, 

 downwards, outwards, and slightly backwards. Hy the structure 

 of the knee-joint this brings the long axis of the tibio-tarsus 

 almost parallel to the long, mesial axis ot the pelvis. Now the 

 tibio-tarsal articulation permits the exact play of the foot, by a 



