Fig. 27.—Right scapula of Dolphin (Tursiops tursio). × ¼. a, Acromion; af, prescapular fossa; c, coracoid; gc, glenoid cavity; pf, postscapular fossa. (From Flower's Osteology.)
Fig. 28.—Side view of right half of shoulder girdle of a young Echidna (Echidna hystrix). × ⅔. a, Acromion; c, coracoid; cb, coracoid border; cl, clavicle; css, coraco-scapular suture; ec, epicoracoid; gb, glenoid border; gc, glenoid cavity; ic, interclavicle; pf, postscapular fossa; ps, presternum; s, spine; ss, suprascapular epiphysis; ssf, subscapular fossa. (From Flower's Osteology.)
the spine, the prescapular lamina, is most extensively developed in such animals as perform complex movements with the fore-limbs. The Sea Lion and the Great Anteater are cited by Professor G. B. Howes as examples of this preponderance of the anterior portion of the scapula over that which lies behind the spine. The general shape of the scapula varies considerably among the different orders of mammals; but it always presents the characters mentioned, which are nowhere seen among the Sauropsida except among certain Anomodonts, which will be duly referred to (see p. 90). The most conspicuous divergences from the normal are to be found in the Cetacea and the Monotremata. In the former the acromion is approximated so nearly to the anterior border of the blade-bone that the prescapular fossa is reduced to a very small area; and in Platanista the acromion actually coincides with the anterior border, so that that fossa actually disappears. In the Whales, too, the scapula is as a rule very broad, especially above; it has frequently a fan-like contour. In the Monotremata the acromion also coincides with the anterior border of the scapula; but the sameness of appearance which it thus presents (in this feature) to the Cetacean scapula is appar-
