A very curious muscle runs into the patagium of the wing, which is that fold of skin which lies between the shoulder and the hand. This muscle is called the patagial muscle. It starts from the shoulder as a fleshy band, but soon ends in two long tendons: one of these follows the upper margin of the patagium, and finally ends in the wrist; the other passes down over the patagium, and ends below in connection with some of the muscles of the arm, and also by being attached in a fan-shaped way to the skin itself. The function of this muscle is to assist in the folding up of the wing when it is, so to speak, put away after use. The tendons in which the latter part of this muscle ends often show a most complicated branching in the patagium; they frequently offer characteristic differences in different birds, and are made some use of by the systematist. The bird has got a biceps to its arm just as we have. It sometimes happens that this biceps gives off a muscular slip, which runs into the patagium and becomes attached to the upper of the two tendons of the patagial muscle. A good deal of stress is laid by certain ornithologists as to whether this biceps slip is absent or present. Several of the common British birds will afford material to the beginner to ascertain for himself some of the chief variations in these and the other muscles of the body. It will be a good exercise to get a few birds, and to carefully dissect two of them, belonging to as widely different kinds as possible, side by side. You might select, for instance, a Crow and a Pigeon, which are fairly extreme types. To revert to our account of the muscular anatomy of a bird, it will be impossible to attempt any comprehensive account of this branch of the subject, because the facts are so appallingly numerous. We shall content ourselves, therefore, with the mention of a highly characteristic bird muscle which occurs in the leg. This muscle is known as the ambiens. This muscle is thin and ribbon-like. It takes its origin from a little process of the pubic bone usually called the prepubic process. From this point it runs along the inside of the thigh until it reaches the knee; it then bends over the knee and comes out on the other side, where it runs down the leg to join the deep flexor muscle of the foot. When this ambiens muscle contracts it pulls upon the flexor muscle, already referred to; the effect of this is that the toes are brought together by the tendons in which the last-mentioned muscle ends. The ambiens is far from being universally present among birds. It is notably absent from the passerine birds (the Sparrows, Crows, Rooks, and small perching birds generally), and from the Hornbills, Toucans, Woodpeckers, and that varied assemblage known as picarian birds. On the other hand, the Storks, Hawks, and most of the larger birds, have the muscle. But among some of these it is absent; thus, the Owls on the one hand, and the Herons on the