. Natural history. Geology; Zoology; Botany. 20 W. P. PTCKAFT. ungual phalanx, while Digit III. is slightly shortened and terminates in a point. The humerus in the adult, like the rest of the wing, has undergone great flattening, as well as marked changes in its extremities. Its distal end has become twisted on itself, so that the radial and ulnar condyles lie one above the other, instead of side by side, and, further, have become reduced so as to form confluent facets, while the olecranon process is now produced backwards into a prominent, triangular spur, bearing two deep grooves for the lod
. Natural history. Geology; Zoology; Botany. 20 W. P. PTCKAFT. ungual phalanx, while Digit III. is slightly shortened and terminates in a point. The humerus in the adult, like the rest of the wing, has undergone great flattening, as well as marked changes in its extremities. Its distal end has become twisted on itself, so that the radial and ulnar condyles lie one above the other, instead of side by side, and, further, have become reduced so as to form confluent facets, while the olecranon process is now produced backwards into a prominent, triangular spur, bearing two deep grooves for the lodgment of sesamoids of large size. The proximal end has also under- gone considerable changes, the most marked of which are the increased size of the glenoid surface of the head and the great size of the fossa trochanterica. The skeleton of this limb is non-pneumatic. The result of these modifications has been to permit the several segments of the wing to be extended so as to form a straight-jointed rod, but one allowing of but little motion between the joints. In the normal wing the hand can be .straightened out upon the forearm, but the latter is always, from the nature of its articulations, bent upon the humerus. But then, of course, in the one case the wing is used as a paddle, in the other for the purposes of flight, though the /' (t-^ ^ S( ,/r7 r/ u T1 Wm\v\ / .^ paddle of to-day, there can be no doubt,was earlier used as a wing. The Tarsal and Metatarsal FIG. 6.—THE DUODENAL LOOP OF A NESTLING EMPEEOB PENGUIN. In the embryo of the Emperor Penguin, to which the wing just described belonged, the tarsus is wholly cartilaginous, but the proximal row, though showing no separate elements, is yet free and is applied in the form of a cartilaginous pad to the bones of the metatarsals The metatarsals are also all free, and, it is important to remark, have the form of perfectly cylindrical shafts, thus showing that the peculiarly broad and semi-distinct metatarsals
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