454 DR. J. MURIE ON THE ANATOMY OF THE WALRUS. 
true, are small, and the latter abnormal in origin; they nevertheless possess some 
interest myologically. 
Left hind foot, with portion of the fibula and tibia, seen dorsally in a 
three-quarter view from the outside, and dissected to expose the 
short, and insertion of the long, extensor muscles, 
Digits, respectively numbered J to V. 7. Tibia. F. Fibula. Tua. 
Double insertion of the tibialis anticus. Z.l.d. Extensor longus 
digitorum. Z.p.h. Extensor proprius hallucis, £.b.d', E.b.d?, E.b.d°. 
The three bellies of the extensor brevis digitorum. P.1,P.1.* Pero- 
neeus longus, belly and tendon. P.b, Peronsus brevis. P.t, Peronzeus 
tertius? P.4.d. Peroneus quarti digiti. P.5.d. Peroneus quinti 
digiti. Abm.d, Abm.d*. Abductor minimi digiti. 
Peroneus quarti digiti (woodcut 6, P.4d)—Compared with the peronus longus, 
peroneus brevis, and peronus quintus, this has a very diminutive muscular belly. It 
arises deeper than, and in close conjunction with, the combined belly of the two latter 
peronei, at the lower fourth and on the outside of the fibula, and it passes behind the 
malleolus in company with them. In front of the os calcis it becomes tendinous; and 
the fine tendon runs inwards and forwards, piercing the fleshy portion of the third belly 
of the extensor brevis digitorum; mingling with its tendon, both proceed to the outer 
side of the fourth digit. 
Peroneus tertius *—This (woodcut, fig. 6, P.t) appears almost as an extra reinforce- 
ment or slip, and, indeed, may be part of the compound extensor brevis digitorum ; 
but, notwithstanding its junction thereto, it is in the main quite free; and from its 
manner of insertion I am inclined to regard it as a displaced peroneus. It is a long 
fusiform slip, which arises muscularly: from the upper and outer posterior end of the os 
calcis, where it is covered by fascia. It runs beneath, or rather crosses under the 
peronei-tendons at the distal end of the calcaneum; and its tendon joins that of the 
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