Key to Table A) Deltoid B) Thigh C) Peronus D) Gastrocnemius ==================================================================== Species |P. major|P. minor| A | B | C | D ---------------+--------+--------+--------+--------+-------+-------- Ptilogonys | 2.42g. | .29g. | .55g. | | | caudatus | 4.94% | .59 | 1.12% | .43g. | .15g. | | | | | .88% | .31% | .96% Ptilogonys | 2.19g. | .28g. | .53g. | | | cinereus | 5.57% | .71% | 1.35% | .30g. | .08g. | | | | .71% | .21% | 1.02% Phainopepla | 1.30g. | .20g. | .30g. | | | nitens | 4.99% | .77% | 1.15% | .28g. | .10g. | | | | | 1.12% | .40% | 1.42% Phainoptila | 3.93g. | .44g. | .92g. | | | melanoxantha | 6.18% | .69% | 1.45% | 1.09g. | .48g. | | | | | 1.61% | .75% | 2.97% Dulus | 2.09g. | .22g. | .50g. | | | dominicus | 4.81% | .50% | 1.15% | .73g. | .18g. | | | | | 1.68% | .41% | 1.01% Bombycilla | 3.85g. | .45g. | .55g. | | | garrula | 5.31% | .62% | .76% | .50g. | .15g. | | | | | .69% | .18% | .59% Bombycilla | 2.58g. | .35g. | .50g. | | | cedrorum | 5.00% | .68% | .97% | .37g. | .10g. | | | | | .73% | .19% | .83% ---------------+--------+--------+--------+--------+-------+-------- _Pectoral Muscles._--The pectoral set of muscles varies but little in the family; flight power is seemingly not dependent upon size of either the pectoralis major or pectoralis minor. The data indicate that the insertion on the humerus, with consequent changes in the relative length of that bone, is more significant in type of flight and over-all flight power than is the actual size of the muscle mass. The deltoid muscle, for example, is smaller in _Bombycilla_ than in members of the other two subfamilies. The humerus in _Bombycilla_ is shortened, and the muscle therefore does not need to be large to accomplish the same powerful stroke that would be accomplished by a longer humerus and a larger, more powerful deltoid muscle. In the case of the deltoid, the shortening of the humerus and the more complex arrangement of the points of insertion have obviated the necessity of enlarging the muscle.