280 ZAGLOSSUS. 
by side to the tarsus, where the soleus tendon passes underneath that of the 
latter to insert on the caleaneum. 
Just medial of the origin of the soleus, at the tip of the fibular process arises 
_a short flat muscle which passing into a long tendon, crosses under the gastro- 
cnemius to the medial side of the leg, and passing through the groove between 
the distal head of the tibia and the naviculare, inserts at the base of the terminal 
phalanx of the first digit. It is also connected with the general fascia of the 
sole of the foot. This muscle is present in a similar relation in the Echidna, 
and is considered the homologue of the plantaris (Plate 2, fig. 4, pla) by Mivart 
and by Westling, an interpretation which is probably correct notwithstanding 
that there is no femoral origin, and that the insertion (at least in the Proechidna) 
is definitely into digit 1. 
The popliteus does not originate from the femur but from fascia between 
it and the long proximal extension of the fibula, and mainly by muscular fibers 
from the medial surface of this part of the fibula itself. It passes as a thick 
triangular muscle to an insertion on the medial edge and ventral part of the 
tibia for a centimeter or more at the proximal end. The same conditions 
obtain in the Echidna. 
Partly underneath the origin of the soleus and extending slightly external 
to it on the head of the fibula arises the chief flexor of the foot, which appears 
to correspond to the flexor longus digitorum (Plate 2, fig. 4, fld). The origin is 
by tendinous fibers from slightly more than the proximal half of the postero- 
external aspect of the fibula. At the tarsus it becomes a stout tendon that inserts 
upon the internal edge of the caleaneum and then spreads out in the broad 
plantar fascia of the foot. Its four main tendons go to digits 1, 2, 3, and 4 
respectively, inserting into the terminal phalanx. A fifth tendon comes off 
from the plantar pad between the tendons to the first and second digits and 
passes to the basal phalanx of the second digit on the external side. A similar 
tendon comes from between those to the second and third digits, and inserts 
on the basal phalanx of the third digit, making thus six tendons from the plantar 
pad. ‘There appears to be no branch to the fifth digit. 
Wedged in between the heads of the soleus and the plantaris and covered 
by them is a very small compressed muscle arising from the lateral margin of 
the proximal end of the fibula. At about half way on the length of the tibia 
it becomes a small tendon that joins the ental margin of the great tendon of 
the flexor longus digitorum, just proximal to the tarsus. This tendon is not 
traceable farther as it is fused with that of the latter muscle. This muscle 
