82 MESSRS. MURIE AND MIVART ON THE 
Tipiauis posticus':—This is a very thin but a very long muscle, with a very long 
tendon; and this is so enclosed by the flexor longus digitorum and flexor longus hallucis 
as to be entirely hidden down almost to the internal malleolus. It arises from the tibial 
surface of the fibula, almost to its summit, and from the interosseous membrane. Its 
tendon is somewhat attached to the distal end of the naviculus, but is finally inserted 
into the proximal end of the plantar surface of the ento-cuneiform. 
In Galago crassicaudatus (Pl. V. figs. 23 & 24, T:p), G. garnettii, and G. allenii there 
is a superficial median tendon upon the muscular fibre almost its entire length; but the 
tendon of insertion commences only above the ankle to the inner side of the malleolus, 
which it crosses, and is attached to the proximal end of the naviculare. 
Popiitevs.—This muscle arises from a pit outside the peroneal condyle by a strong 
tendon which runs beneath the external lateral ligament. ‘The muscular fibres spread 
out as usual, and are inserted into the posterior surface of the tibia above the origin of 
the flexor longus digitorum. 
Found in the same condition in all the Lemurs and Galagos, also in Nycticebus’, 
Loris, Perodicticus *, and Tarsius ‘—and in Cheiromys, although Owen does not mention 
it. Figured in Galago crassicaudatus (Pl. V. figs. 23 & 24, and Pl. VI. fig. 28, Po). 
Rorator FIBuL# (PI. V. figs. 22 & 23, and Pl. VI. figs. 28 & 29, R. fb).—This small 
but very peculiar muscle is somewhat rhomboidal in shape, and extends from the 
summit of the posterior surface of the tibia to the anterior surface of the fibula, its 
insertion into the fibula being rather more vertically extended than is its origin from 
the tibia. Its fibres pass downwards and outwards, and therefore in an opposite 
direction to those of the interosseous membrane, the upper part of which membrane 
appears to be absent. The posterior surface of the rotator fibulee is covered by the 
popliteus, the flexor longus hallucis, and the tibialis posticus, while its anterior surface 
is in contact with and covered by the peroneus longus, and by the very singularly 
situated upper end of the flexor longus digitorum. 
The muscle described by Professor Owen‘ as existing in Phalangista has its fibres 
inclined in an opposite direction to those of our muscle; and Professor Huxley, in his 
recent Hunterian Course of Lectures, has announced the same fact with regard to the 
Wombat; and as we believe this Lemurine muscle is as yet altogether undescribed, we 
propose to bestow on it the above appellation. 
We have carefully verified the existence of this muscle in both legs of each of the 
species of Lemur and Galago dissected by us, but could find no trace of it in Nycticebus 
and Loris; and Burmeister and Owen are silent as to its existence in Tarsius and 
Cheiromys. Nevertheless in our specimen of Cheiromys we find this muscle fully as 
' Cuvier, pl. 70. fig. 3, 6" (in Lemur varius). 2 Loe. cit. p. 251, fig. 5, pv. 
* Loe. cit. p. 43, pl. iii. fig. 15, a. * Loc. cit. p. 75, tab. 4. fig. 5, no. 23. 
* Todd’s Cyelop. of Anat. and Physiol. vol. iii. p. 291, fig.113,i. In the text the fibres are spoken of as 
passing “ outwards and downwards ;” but the accompanying figure contradicts this statement. 
