280 ZAGLOSSUS. 



by side to the tarsus, where the soleus tendon passes underneath that of the 

 latter to insert on the calcaneum. 



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 ceiftuneter 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 digit orum (Plate 2, fig. 4, fid). 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 calcaneum 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. X 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 



