Page:Quarterly Journal of the Geological Society of London, vol. 34.djvu/169

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PROF. OWEN ON ARGILLORNIS LONGIPENNIS.
129

note:—"This change in the name has been made in the paper referred to whilst passing through the press."

EXPLANATION OF PLATE VI.

Fig. 1.
Argillornis longipennis. Proximal end of left humerus, palmar surface.
2.
The same, aneonal surface.
3.
Proximal end of right humerus, proximal surface.
4.
Diomedea exulans. Proximal end of left humerus, anconal surface.
5.
The same, palmar surface.
6.
The same, proximal surface.
7.
Argillornis longipennis. Proximal portion of the shaft of left humerus, anconal surface.
8.
The same, radial border.
9.
The same, transverse section distad of pectoral ridge, showing size of pneumatic cavity and of its compact wall.
10.
Distal portion of the shaft of left humerus, transverse section above l, fig. 11.
11.
The same, palmar surface.
12.
The same, radial border.
13.
Diomedea exulans. Proximal portion of shaft of left humerus, anconal surface.
14.
The same, transverse section distad of pectoral ridge.
15.
Distal end of left humerus, palmar surface.
16.
Argillornis longipennis. Ulnar side of distal end of fig. 7, showing a groove, o, leading to the pneumatic cavity.
17.
Diomedea exulans. Corresponding side of fig. 13, showing the groove leading to the "foramen arteriæ nutritiæ" in Diomedea. This additional evidence of the humeral nature of the portion of bone of Argillornis (fig. 7) was detected and pointed out to me by the accomplished artist Mr. C. L. Griesbach, F.G.S.

Discussion.

Prof. Seeley said that it was impossible to form a judgment upon the matters brought forward by Prof. Owen without an opportunity of closely examining the specimens. At the same time he had no doubt that the remains were those of a bird; and he had himself, several years ago, obtained in the same locality a bone (a cast of which he exhibited) which he regarded as part of the tibia of a very large bird, and referred to a genus which he called Megalornis. At the time that his paper on this specimen was written, he was not aware that the name had been already appropriated, although he had consulted competent ornithologists on the subject. With regard to the specimens described by Prof. Owen, there might perhaps be some doubt whether all of them belonged to the fore limb, since two of them, he thought, closely resembled parts of a tibia such as the tibia of Megalornis. If this resemblance were not an accidental coincidence, the remains exhibited might furnish indications of two genera.

The Author, in replying, remarked that the bone which Messrs. Bowerbank and Seeley had held to be "tibial," and of an Emuine