Now, in the wing of the pigeon, or any other bird, the first and fifth digits are wholly aborted; the second is rudimentary, and carries the so-called 'bastard wing;' whilst the third and fourth {182} digits are completely united and enclosed by skin, together forming the extremity of the wing.

So that in feather-footed pigeons not only does the exterior surface support a row of long feathers like wing-feathers, but the very same digits which in the wing are completely united by skin become partially united by skin in the feet; and thus, by the law of the correlated variation of homologous parts, we can understand the curious connexion of feathered legs and membrane between the outer toes." Irregularities in the circulating system are far from uncommon, and sometimes illustrate this homological tendency.

My friend and colleague Mr.
George G.Gascoyen, assistant surgeon at St.Mary's Hospital, has supplied me with two instances of symmetrical affections which have come under his observation.
In the first of these the brachial artery bifurcated almost at its origin, the two halves re-uniting at the elbow-joint, and then dividing into the radial and ulnar arteries in the usual manner.

In the second case an aberrant artery was given off from the radial side of the brachial artery, again almost at its origin.

This aberrant artery anastomosed below the elbow-joint with the radial side of the radial artery.