358 MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 
the specimens examined, but not seen in the Dolphins generally, is a rough rounded 
tubercle, projecting downwards from near the middle of the radial border, and connected 
by a broad ridge with the lower part of the tuberosity. Immediately beyond this 
tubercle, the border of the shaft is deeply hollowed out. ‘The distal end is divided 
nearly equally into two rugged and irregular hollowed facets, meeting at an angle of 
about 150°. The radial facet is considerably broader than that for the ulna. 
In both the aged animals from the British coasts, the extremities of the radius and 
ulna are ankylosed to the contiguous surfaces of the humerus; and this is partially 
the case on the left side in the Tasmanian skeleton, but not on the right; nor has 
it occurred in either of the other specimens sent by Mr. Crowther. It must be observed, 
however, that in neither of these has the epiphysis forming the head of the humerus, 
and which includes nearly the whole of the tuberosity, coalesced with the shaft. In 
none of the specimens is there any trace of a distal epiphysis to the humerus. A con- 
siderable difference will be observed in the form of the two humeri figured in 
Plate LXI. 
The radius and ulna, in nearly all the specimens examined, are united together at 
their proximal extremity, and in one case (the Caithness skeleton) also at the distal end. 
In the greater part of their length there is a considerable space between them, chiefly 
occasioned by the narrowing of the middle part of the ulna ; for the corresponding border 
of the radius is nearly straight. 
Each bone has an epiphysis at either extremity, that at the proximal end being a thin 
plate, comprising only the articular surface, and early ankylosed, the other being larger 
and more tardy both in ossification and in union with the shaft. In all the specimens 
in which the head of the humerus is still free, this epiphysis is also ununited; and its 
rugged, irregular surfaces, and small size compared with the extremity of the bone to 
which it is applied, show that the portion preserved is only the ossified nucleus of a larger 
cartilaginous mass. In the absence of the epiphyses the surfaces of the lower ends of 
the bones are deeply concave. 
The ulna is lighter and more compressed, as well as shorter, than the radius. It is 
very broad at the distal extremity, and, being contracted at the middle, has rather an 
hourglass-form. From its free border, near the proximal end, rises a well-developed, 
compressed olecranon process, expanding as it rises, and terminating in a semicircular 
margin. 
The radius has far less character about its outline, the borders being approximatively 
parallel. 
The free or distal end of the lower epiphysis of both bones is ers into two facets, 
conforming with the outline of the contiguous carpal bones. 
