. Elementary text-book of zoology. MAMMALIA. 539 cartilage, it probably represents the clavicle and precoracoid joined in one. Its distal end forms an attachment for the humerus and it is also joined by a ligament to the scapula. The scapula is long and narrow and assists, as usual, in bearing the humerus. The bony connection of " clavicle," episternum, ribs and vertebral column, assisted by the scapula, forms a solid fulcrum for the fore-limb. The humerus is quite unique. Short and stout, it is expanded into lateral crests and processes. The radius and ulna are also short and stout
. Elementary text-book of zoology. MAMMALIA. 539 cartilage, it probably represents the clavicle and precoracoid joined in one. Its distal end forms an attachment for the humerus and it is also joined by a ligament to the scapula. The scapula is long and narrow and assists, as usual, in bearing the humerus. The bony connection of " clavicle," episternum, ribs and vertebral column, assisted by the scapula, forms a solid fulcrum for the fore-limb. The humerus is quite unique. Short and stout, it is expanded into lateral crests and processes. The radius and ulna are also short and stout and the olecranon is long, increasing the mechanical advantage of the extensor muscles. Fig. 372.—Anterior View of Pectoral Girdle and Lime or THE Mole. ,. Note the shortened limb, powerful clavicle and humerus and broad scoop-like manus. The carpal bones are compact and the whole manus is broad and flat. There are five short digits with strong claws. Inside the first digit is a falciform bone which some authorities regard as a prepollex or sixth digit. What- ever its homology, it assists -greatly in adding to the "expanse" of the hand. The movement of digging, like those of swimming and flying, involves a great development of the pectoral muscles; and in correlation with this there is a median keel or ridge on the sternum at their point of origin {cf. bat and bird). All the above structural features point to the burrowing function of the fore-Hmbs. With regard to the forward extension of the episternum, and with it. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Masterman, Arthur Thomas. Edinburgh, E. & S. Livingstone
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