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Show 486 DR. R. W. SHUFELDT ON [Nov. 16, extensors, just above the sole on the one side, and which passes above the distal trochleae on the other. A s we pass the muscles we have described for this limb in review, it will at once be recognized that the list is unusually complete. All the ordinary muscles of the thigh are present as found in birds, and all highly developed. In the leg marked specialization and organization are everywhere evident, while exceptional muscles are here, too, fully represented. This complexity by no means diminishes as w e proceed towards the foot, for the arrangement of the tendons as they course down the tarso-metatarsus and the special musculature of this division of the limb is manifestly indicative of high organization. Finally, we have the complex insertional extremities of the intricate system above laid before us in the foot; and the most exquisite examples of adaptation, compactness, and final requirements are to be seen throughout the structure on every hand. Notes on the Arterial System. Fortunately the evisceration that had been performed upon my specimen before it came into m y hands has not injured the heart and great vessels. So by a careful dissection I a m enabled to state that there are two carotids in Geococcyx californianus, and that their arrangement and the method of their branching at the base of the heart is normal. In other words, the bird in this respect is to be included with the Aves bicarotidinw normales, as defined by Garrod. I would remark, however, that the carotids come off from the innominates at points considerably further removed from the heart than that anatomist depicts them in his diagram of this condition. The branching is the same, however, and no doubt Mr. Garrod's figures were intended to illustrate this point above all others, to which end they serve an excellent purpose. Turning to the arterial system in the pelvic limb, I find that the main artery of the leg is the sciatic. This agrees with the vast majority of birds, and, so far as I a m aware, it is only in Centropus phasianus among the Cuculidae that the rare condition of the femoral artery being the main one obtains. Of the Bursa Fabricii. As I said at the beginning of this memoir, Forbes has already called our attention to the peculiarity of form of this structure in .the young of Geococcyx affinis (P. Z. S. 1877, p. 312), and says that it completely disappears in the adult. I can verify this statement so far as the specimen before m e is concerned, for in it this bursa is not present, while the region otherwise is characterized as we find it in the adults of the Centropodince. The Trachea. (Plate XLIII. figs. 3 and 4.) For the entire length of this subcylindrical tube, the osseous rings which compose it fail to meet in the longitudinal median line posteriorly. |
