342 MESSES. A. AND E. NEWTON ON THE OSTEOLOGY OE THE SOLITAIEE. 
creasing in thickness from near the proximal end, and widening laterally very consider- 
ably towards the distal, where it expands to nearly double the original diameter of the 
shaft, and in the larger specimens (males'?) is clothed on the side furthest from the 
ulna for nearly half an inch by an irregularly-shaped bony growth, having at first sight 
much the appearance of a stalagmitic encrustation, to which further reference will be 
made presently. In the smaller specimens the entire bone, though nearly half an inch 
shorter, is considerably thicker than in Didus, especially towards the distal end, in which 
part there is little resemblance between the two forms. The proximal articular surface 
though larger is much as in Didus. 
The ulna (Plates XIX. figs. 93, 96, XX. figs. 134, 135), of which forty-one specimens 
are present, is cylindrical, straighter, and thicker than in Didus, with the muscular de- 
pression, described by Professor Owen, much less deeply marked, smaller, and situated 
more distally. In some specimens as many as ten impressions of the roots of the secondary 
wing-quills can be distinctly traced along the anconal surface, besides three elongated 
and transversely-directed depressions towards the distal end. On the radial side of these 
depressions there is present in two or three large and well-preserved specimens a small 
bony tuberosity. 
Very many of the largest (male]) specimens of both ulna (Plate XX. fig. 135) and 
radius bear marks of fracture and healing during the bird’s life. 
Perhaps the most interesting of the bones in the whole collection is the metacarpal 
(Plates XIX. figs. 87-90, XX. fig. 131, XXII. fig. 148), of which no specimen belonging 
to any Didine bird has hitherto been seen. We have here thirty-two. That it would 
be very short was a safe inference from what we know of it in other flightless birds ; 
but it could hardly have been expected to obtain from it such a singular confirmation 
of Leguat’s statement regarding a remarkable peculiarity in the “ Solitaire ” as 
observed by him, nor that it should furnish an explanation of the curious bony growth 
on the distal end of the ulna and radius already mentioned as presented by the spe- 
cimens of supposed males. All the perfect specimens of the metacarpal have on 
the radial side a more or less spherical bony knob or callus-like mass developed 
immediately beyond the proximal end and the pollex, which last would appear to 
be thrust away by it to some extent. This knob in the larger specimens, which we 
suppose to have belonged to males, is out of all proportion to anything of the kind 
yet known in ornithology. It is subject to a good deal of variation in form and to a 
less degree in size, sometimes projecting rather downward than laterally, but in all 
cases more or less pedunculate. In the largest (male ]) specimens its longest diameter 
is about half the length of the entire metacarpal, and its transverse breadth in any 
direction is not much less. The metacarpal itself is pneumatic and light, the largest 
specimen weighing, the knob and all, just about a quarter of an ounce; but the knob, 
which has been broken off from another specimen, weighs as much as the remainder. 
The appearance of the knob is much that of diseased bone ; it has probably been covered 
by a cartilaginous integument, which may have extended to the somewhat similar though 
