514 ■ DE. J. IHXTIIE ON THE AJSTATOMY 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, foui* 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 Eadius. Throughout the Pinnipedia the ulna is hatchet-shaped, altogether 

 flattened, especially the olecranon (as the blade). Slight modifications distinguish 

 the difierent families and genera (witness Cuvier and De Blainville's illustrations &c.). 

 In Otaria juhata 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 vii'tually 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 cimeiform 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 walkuig. 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 



