80 MESSRS. MURIE AND MIVART ON THE 
Achillis, and ultimately behind it, passing beneath the os calcis (from which and from 
the lowest part of the tendo Achillis it is separated by a bursa), and becomes continuous 
with the plantar fascia. 
Figured by us in Galago crassicaudatus (Pl. II. fig. 3, and Pl. VI. fig. 25, Pla). 
Kingma says that he sought in vain for this muscle in G. peli’. 
It was absent in the specimens of Nycticebus and Loris examined by us, and, 
according to Van Campen’s dissection, is absent in the Potto?. 
In Tarsius’ the plantaris arises from the external condyle side by side with the 
gastrocnemius, and passes down, attaching itself to the calcaneum and plantar surfaces 
of the foot. 
The FLEXOR LONGUS DIGITORUM* is a very long, but rather small, muscle arising from 
the upper two-thirds of the posterior surface of the tibia, below the popliteus, and from 
the peroneal side of the head of that bone, its uppermost part ascending between the 
tibia and the rotator fibule, and above and across the interosseous membrane to the 
front of the leg, so as to be in contact with the summit of the posterior margin of the 
tibialis anticus. It is inserted by a strong tendon which passes on the tibial side of the 
tendon of the flexor longus hallucis. It then gives off a delicate tendon which joins a 
corresponding and larger one from the flexor longus hallucis (to form the flexor tendon 
of the hallux), and afterwards becomes intimately blended with the main part of the 
tendon of the last-mentioned muscle, the two giving rise ta the four perforating tendons 
of the four outer digits, but the flexor longus digitorum forming almost exclusively that 
of the fifth digit, and but a small part of those going to the second, third, and fourth 
digits. 
Shown in the Grand Galago, Pl. II. fig. 3, in Pl. V. figs. 22, 23, & 24, and Pl. VI. 
figs. 25, 28, & 29, F.l.d. 
We find in Loris gracilis precisely the same condition as in Nycticebus (presently to 
be described), with the exception that the tendons to the four outer digits are all given 
off at the same height. 
In Nycticebus tardigradus® the flexor longus digitorum has three origins and three 
bellies—one origin from the inner condyle of the femur, another from the inner 
border of the tibia joining the last, and the third origin is from the posterior surface of 
the tibia below the popliteus. 
This muscle is described in Perodicticus® as consisting of two separate parts uniting 
into a common tendon in the plantar aspect of the foot, and representing both the 
flexor longus digitorum and flexor longus hallucis. It springs from the tibia, fibula, 
and interosseous membrane, but not from the femur. In this respect, both in its origin 
1 Loe. cit. p. 31. ? Loe. cit. p. 44. 
* Loc. cit. p. 76, tab. 4. fig. 7, no. 29, and tab. 5. figs. 8, 9, & 10, no. 29. 
* Cuvier, pl. 70. fig. 3, . (Z. varius), and pl. 67. fig. 2, « (Loris gracilis). 
> P. Z. 8. 1865, p. 252, figs. 5 & 6. ® Loc. cit. pp. 44, 45. 
