42 The Phylogeny of the Crura] Flexors 



to it is of great importance in determining the true significance of the 

 muscle, for they indicate, apparently, a primary attachment of the 

 muscle to the femur. The tendon, indeed, represents the proximal 

 portion of the muscle which has undergone degeneration in association 

 with a new attachment made by the muscle below the knee joint, the 

 resulting condition being strictly comparable with what has occurred 

 in connection with the peroneus longus of man, this muscle having 

 similarly shifted its upper attachment from the femur to the fibula, its 

 upper part being represented by the external lateral ligament of the knee 

 joint. 



Pio. 3. — Transverse section through the upper part of the crus of Scincus sp. 

 F, fibula ; f, ramus superficialis fibularis ; fc, fibular cutaneous nerve ; / interosseus ; 

 TO, ramus superficialis medialis ; p, ramus profundus ; pc, cutaneous branch from ramus 

 profundus; P//-//A plantaris profundus II-III ; Psa, plantaris superficialis accessorius ; 

 Psl, plantaris superficialis lateralis ; Psm, plantaris superficialis medialis ; Pst, plantarls 

 superficialis tenuis ; Tj tibia. 



An examination of the origin of the plantaris superficialis medialis 

 as described for other lacertilia seems to give support to this view. It 

 is true that throughout the reptilia in general the muscle takes its origin 

 from the tibia. In Euprepes, however, Plirbringer, 70, describes it, 

 under the name of the gemellus internus (epitrochleo-tibio-metatarsalis 

 ventralis) as arising both from the head of the tibia and from the inter- 

 nal condyle of the femur, and, according to Gadow, 82, it (gastroc- 

 nemius, caput internum) arises in Ophryoessa principally from the pos- 

 terior surface of the internal condyle, only a few fibres taking origin 

 from the tibia. It is clear then that one is dealing here with a muscle 

 which M'as either primarily attached to the femur and in the majority 

 of the reptilia has made a secondary connection with the tibia, or else was 

 primarily attached to the tibia and has secondarily migrated, so far as 

 its origin is concerned, upward to the femur. 



There seems to be little question but that the former of these two 



