The appendicular muscles of Necturus maculosus. 415- 



b) extenso r tibialis profundus (etp). This portion lies 

 medial to the former and is wliolly covered by the femorometatar- 

 salis. It arises from the distal margin of the distal epiphysis of the 

 femur, about midway between the two condyles and directly beneath 

 the origin of M. femorometatarsalis. This origin, tendinous at first, 

 becomes muscular almost immediately and the fibers insert along 

 the greater part of the fibular margin and over nearly the fibular 

 half of the dorsal aspect of the tibia, including in length the most 

 of its shaft. 



This entire muscle, although in detail strikingly like its homolog in 

 the forearm, differs from it in the absence of a nerve running between 

 the two portions. AVhat this failure may signify in the consideration of 

 serial homology cannot of course be ascertained until the nerves of the 

 two appendages have been thoroughly studied and homologised, but the 

 nerve is not a very important one and its failure can hardly be considered 

 as a serious obstacle to the homologisation of the tibial and radial ex- 

 tensors. 



M. supinator (s). This muscle is easily distinguished since 

 it is the only one on the dorsal aspect of the limb that is obliquely 

 placed. The terminal portion alone is superficial and may be seen 

 emerging from beneath the femorometatarsalis upon the tibial 

 side; the remainder is concealed by this latter muscle, which must 

 be removed in order to expose it. It is a little larger than its 

 homolog in the forearm, and extends as far as the fibula, from the 

 distal tibial angle of which it possesses an origin. The two other 

 origins are precisely as in the arm, viz: from the tibial margin 

 and a bit of the dorsal surface of the fibulointermedium, and by 

 a deeper slip from the centrale. The muscle is inserted by a tenclon 

 into the tibial margin of metatarsale II, near the base of the bone, 

 and thus acts as an abductor of the digit, completing the System 

 formed by the tendons of insertion of the femorometatarsalis and 

 its accessory slip. 



Owing to its mode of insertion this muscle has been designated by 

 St. John Beooks the "extensor metatarsi hallucis". Hoffmann calls it 

 M. fibulae metatarsus II. Its identity with the supinator of the anterior 

 limb is beyond question. 



M. extensor fibularis (efb). This muscle occupies the 

 outer (fibular) margin of the leg and is partly overlapped by the 

 femorometatarsalis. It arises from the fibular condyle of the femur. 

 and runs down over the dorsal aspect and free margin of the fibula. 

 The more superficial and marginal fibers are the longest, and 



