DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 577 
inner and posterior aspect of the limb. About an inch above the ankle-joint a strong 
tendon is given off; this passes in a groove on the inner side of the os calcis, and as it 
reaches the sole of the foot it is covered and intimately united with the superficial 
plantar fascia. 
At the distal end of the caleaneum the tendon enlarges and thickens, and muscular 
fibres are found on its deep surface; these may represent the flexor brevis digitorum 
(F.2.d, fig. 36). From these muscular fibres four tendons are derived. The first, highest 
and innermost tendon goes to the second digit, forming the perforated tendon of that 
digit; the second proceeds to the third digit, the third to the fourth digit, and the 
fourth to the fifth digit. The insertions of these perforated tendons are the distal ends 
of the second phalanges; they do not split, as is commonly the case, to permit the 
perforans to go onwards, but they form a strong tunnel or tube of fascia for about an 
inch and a half, in which the perforans is enclosed, 
The plantaris, through the elongation of the flexor brevis digitorum, is a direct 
flexor of the four outer digits; and it appears to be this muscle which bends the digits 
when the animal scratches its body, shown in woodcut No. 3, upper middle figure, and 
in woodcut No. 4. It also draws the toes together, when overlapping takes place (see 
Pl. LXVII. fig. 3). 
Lumbricales——These are very large and numerous. They arise altogether broadly 
from the plantar surface of the united plantar fascial expansion of the long flexors 
(fig. 37, L* to L*). Separate, long fusiform muscular bellies, ending in tendons, are 
given off to each of the digits; but there is an additional muscle to the little toe; hence 
there are six lumbricales altogether. 
The first is given off highest, from between the long flexor tendons of the hallux and 
second digit; it is inserted into the peroneal side of the first phalanx of the great toe. 
The second arises between the long flexor tendons of the second and third digits; this 
one ends in the perforated tendon of the second digit derived from the plantaris. The 
third and fourth arise together, very fleshy, superficial to the third and fourth long 
flexor tendons; and their fleshy bellies seem to run into or join the (tunnel-like) per- 
forated tendons of the third and fourth digits supplied by the plantaris. The fifth 
lumbricalis springs from the peroneal side of the fourth lumbricalis, and is inserted 
into the tibial side of the proximal end of the first phalanx of the fifth digit. The sixth 
lumbrical muscle is derived from the outermost tendon of the flexor longus digitorum. 
It is inserted along with the fifth lumbricalis. 
Flexor longus digitorum.—The fleshy belly of this muscle is of moderate thickness, 
and about equal in bulk to that of the flexor longus hallucis, this last partially covering 
it (figs. 36, 37, F/.d). It lies in the deepish hollow between the tibia and fibula, and 
arises from the lower two thirds of the shaft of the fibula and the lowermost third of 
the tibia and the intervening interosseous membrane. From the muscular belly a 
strong flattish tendon is derived just at the ankle-joint; this runs in the groove between 
4n2 
