514 DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 
axis of the three-faced shaft is nearly perpendicular, though at first sight it does not 
appear so, the deltoid projection giving it outwardly somewhat the contour of the 
letter S. The latter forms a thick anterior projecting and somewhat laterally com- 
pressed plate of bone extending from the root of the unusually greater tuberosity 
downwards, mesially, four fifths the length of the shaft. Head and neck sessile. Con- 
dyloid ridges short, but giving great lateral breadth to the lower half of shaft. Inner 
condyle most marked; eminentia capitata and inner trochlear eminence the reverse. 
The further positions of the bones of the elbow-joint, and their singular gliding 
movements upon each other, I discussed when treating of the ligamentous system 
(consult pt. ii. vol. vii. p. 581). 
Ulna and Radius. Throughout the Pinnipedia the ulna is hatchet-shaped, altogether 
flattened, especially the olecranon (as the blade). Slight modifications distinguish 
the different families and genera (witness Cuvier and De Blainville’s illustrations &c.). 
In Otaria jubata the outer extensor surface of shaft is gently convex in its axes, the 
inner flexor is concave; distal epiphysis conical. The even-surfaced greater sigmoid 
notch is almost vertical, with the exception of a small inferior projection (=the coronoid 
process) upon which the inner knuckle of the humerus plays; and on the radial side 
of this projection an oblique shallow concavity represents the lesser sigmoid notch. A 
widish inward scoop separates the humeral articulation from the top of the olecranon 
process, which latter, thinning, sweeps backwards, terminating in a dependent angular 
process. The radius has a well-defined neck, short but large and wide shallow head. 
From the upper third the roundish shaft widens and flattens to its massive lower 
extremity, 2} inches broad, with thickness in proportion, 
Carpus, Metacarpus, and Phalanges. Of the seven carpal bones the amalgamated 
scapholunar is the most remarkable, on account of its great size and of its claiming the 
major share of the articular surface of the first row of bones. It is in opposition with 
all the bones of the second row, the cuneiform, and radius, in all six; but it plays 
against these virtually by three faces. The radial is large and convex; the face in con- 
tiguity with the os magnum and unciform is somewhat vertically scooped, a mesial ridge 
defining the province of each bone, whilst the cuneiform impinges against the posterior 
corner of the latter; lastly, the trapezio-trapezoidal is extensive, rhomboidal-outlined, 
concave from without inwards, and convex from above downwards. It is this peculiar 
disposition of the latter, in unison with a certain oblique or excentric movement of the 
parts, which enables the animal to use its fore flipper on land as a foot; for the proximal 
carpal row is then raised from the horizontal basal line, as in a great measure is the 
unciform. Thus the wedged-in magnum, the trapezoides, and the trapezium of the 
carpals form the base of support; and that also accounts for the singular radial flop 
with which the manus is laid down in walking. According to the amount of bend of 
the wrist-joint, so does the cuneiform in a lesser or greater degree come into connexion 
with the bones. Its postero-outer face receives the pisiform and point of the ulna in a 
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