291, ♀ ad., same locality and date. Length, 4.70; extent, 7.10; wing, 2.37; tail, 2.09. Same remarks.
(To be continued.)
NOTES ON THE OS PROMINENS.[[47]]
BY FREDERIC A. LUCAS.
My attention was first directed to this bone by Dr. Shufeldt’s article in this Bulletin for October, 1881, and subsequently by Mr. Jeffries’ paper in the number for January, 1882. With the view of ascertaining in what birds the os prominens is present, and what is its use, I have since examined quite an extensive series of birds. Lack of time has prevented as extended an examination as could be wished for; and as regards discovering any special use for this sesamoid, it must be confessed that the results of the investigation are not wholly satisfactory, being rather negative than positive in their character. But such as they are, they are submitted, in the hope that they may prove of service to some better skilled physiologist.
Through a lack of good material Dr. Shufeldt failed to discover the existence of the os prominens in any of the Owls, but it would seem to be specially characteristic of the Bubonidæ, since it is present in one particular shape, and with a constant mode of articulation, in the following species of that family: Ketupa ceylonensis, K. javanensis, Bubo ignavus, B. bengalensis, B. virginianus, Scops brasilianus, S. asio, Nyctea scandiaca, Ninox albigulare, Asio otus, Syrnium nebulosum, and S. uralense. It is not present in Strix flammea or S. perlata, and should it prove to be present in other genera of the Bubonidæ than those noted above, it may serve as an additional, though trivial, point of distinction between the families Bubonidæ and Strigidæ.
Left wing of Bubo virginianus, from below (reduced one third).
r, radius; u, ulna; c, cuneiform; s, scapho-lunar; os p, os prominens; epa, tendon of extensor patagii longus.
The accompanying cut, drawn from a fresh specimen of B. virginianus, explains the form and position of the os prominens.
It will be noticed that it is situated on the anterior surface of the distal end of the radius, and runs almost parallel with that bone, instead of standing erect as in the Falconidæ. The radial portion of the tensor patagii longus terminates in the os prominens, and is not continued to the first metacarpal.