78 MESSRS. MURIE AND MIVART ON THE 
is inserted into the extensor sheath of the fourth digit; thus the muscle, though it 
arises externally to the peroneus quinti digiti, is inserted internally to it. 
L. varius, L. xanthomystax, and L. nigrifrons (P1. VI. fig. 27, P.4.d) quite resemble 
L. catta as regards this muscle. 
Not present in Galago crassicaudatus, G. garnettit, or in G. allenit. 
Neither this muscle nor that of the peroneus quinti digiti are mentioned either by 
Van Campen in Perodicticus, or by Owen in Cheiromys. Nevertheless in our specimen 
of the last-mentioned animal we found it distinctly present, and exactly conditioned as 
in L. catta. It is, however, described by Burmeister’ under the name extensor longus 
quarti digiti. 
PERONEUS QUINT! DIGITI2,—This is a very small muscle indeed, with a long and very 
delicate tendon. It arises from the anterior surface of the fibula below, underneath the 
peroneus longus, but above the origin of the peroneus quarti digiti. The delicate 
tendon passes down the outside of the tendon of the peroneus brevis, and is inserted into 
the peroneal side of the extensor sheath of the fifth digit. 
In L. varius and L. nigrifrons (Pl. VI. fig. 27, P.5.d, P.5.d*) exactly the same con- 
ditions obtain. 
Figured in Galago crassicaudatus (P1. I. fig. 3, and Pl. VI. fig. 25, P.5.d), where, as 
in G. garnettii, it has a similar origin and insertion to that in L. catta, but its tendon 
keeps to the inner side of that of the peroneus brevis until after having passed the ankle. 
In G. allenti the extreme tenuity of the tendon is alone remarkable. 
The peroneus quinti digiti exists in Nycticebus tardigradus* ; but we did not find it, or 
the peroneus quarti digiti, in Loris gracilis. 
Meckel* seems to have had both the peroneus quarti and quinti muscles in view 
when alluding to a third peroneus with tendons to the fourth and fifth digits being 
present in the Lemurs. 
As has been said, Van Campen is silent as to its existence in the Potto. 
In Tarsius it is described by Burmeister’ as the extensor longus digiti minimi. 
In Cheiromys we found this muscle exactly similar to its condition in L. catta. 
a. Tibio-fibular Region of Leg (flexors). 
Gastrocyemius’.—This muscle is rather small, and arises by two heads of nearly 
equal size, each with a sesamoid bone. The two fleshy bellies unite in the middle of 
the leg with the strong tendo Achillis, which is inserted, as usual, into the tuberosity of 
the os calcis. 
* Loe. cit. p. 79, tab. 4. fig. 5, no. 38, and tab. 5. fig. 6, no. 38. 
* See Cuvier, pl. 70. fig. 1, e? (Z. varius). > P. Z.8. 1865, p. 250. 
* Vol. vi. p. 438. ° P. 79, tab. 4. fig. 5, no. 37, and tab. 5. fig. 6, no. 37. 
* Cuvier’s * Myologie,’ pl. 70. figs. 1 & 8,a; in Tarsius, pl. 67. figs. 1 & 2,a; and in Cheiromys, loc. cit. 
p. 66, pls. xxiv. & xxv. figs. 27, a, b. 
