164 ON FOSSILS FROM NEW ZEALAND 
not more than 3ths of an inch. At this part it is very rough and 
irregular for a space of %rds of an inch, forming a facet with which 
the anterior face of the olecranon was connected. The superior part 
of the posterior face is excavated by a deep cavity; but I suspect 
this to be an accident arising from the destruction of the loose, 
cancellated, bony tissue of this region. 
The outer face of the bone is slightly convex from before 
backwards; concave from above downwards, owing to the great 
projection of the tuberosity of the humerus outwards. 
The inner face (fig. 4) exhibits, above, the articular head, which 
descends upon it, anteriorly, the deep longitudinal groove to which I 
have referred above, and posteriorly, opposite the lower end of this, 
a roughened elevation. 
Inferiorly, the inner face is flat; superiorly it is concave, owing 
to the projection inwards of the articular head. This looks upwards. 
and inwards; it is smooth, convex, and pyriform, the small end 
being turned outwards and upwards. Its greatest length is 1} inch, 
its greatest breadth 1 inch. Externally it is separated by a shallow 
curved depression from the tuberosity. 
The distal end of the bone presents two articular facets for the 
radius and ulna, which might be represented by two half-ovals 
united by their straight edges, in a ridge which traverses the distal 
end transversely, and is nearer its posterior than its anterior end. 
The anterior or radial facet, in fact, measures {ths of an inch in 
length, while the posterior or ulnar does not exceed 3ths. The 
anterior facet looks downwards and slightly forwards, the posterior 
downwards and slightly backwards; the latter passes into the ole- 
cranar facet, which, looking directly backwards, is of course almost 
at right angles with the proper ulnar facet. 
One of the most remarkable features presented by this bone is its 
slenderness, the long diameter being to the antero-posterior diameter 
of the distal end as 23 to 1. 
In Salena, Balenoptera, Delphinus, Orca, and Hyperoodon, the 
antero-posterior diameter of the distal end bears a very much greater 
proportion to the length of the humerus. Thus, for instance, in a 
Delphinus tursto in the Museum of the College of Surgeons, whose 
humerus has nearly the same length as that of the fossil, viz. 34 
inches, the antero-posterior diameter of the distal end is 24 inches, 
or the two diameters are as 13 to 1; and the corresponding bones 
in such species of the other genera mentioned as I have examined 
have similar or even broader proportions. 
In a skeleton of Monodon monoceros, between 9 and 10 feet long, 
