THE MUSCLES OF THE LOWER EXTREMITY. 229 



In our Geococcyx callfornianus the tibialis ijosticus 

 is a veiy slender muscle, but closely resembles tlie same 

 muscle as I have found it in all other birds which I have 

 examined for their myology. 



As in a number of the Passeres, we find it here to 

 arise from the aiitero-lateral aspect of the shaft of the 

 fibula below the tubercle for the insertion of the biceps 

 Hexor crurisy from the interosseous membrane between 

 the leg-bones, from the contiguous surface of the shaft of 

 the tibia, and, finally, from the fascia separating it from 

 the deep flexors of the leg. The fibres pass directly down 

 the outer side of the tibia as a long, slender, fusiform 

 muscle. At the lower fourth of the shaft of this bone 

 they terminate in a small tendon, wdiich, passing in 

 front of the external malleolus, crosses the ankle-joint 

 to become inserted into the supero-external rim of the 

 summit of the tarso-metatarsus. 



116. The jiexoT perforatus indicis secundis pedis ^ is 



vorletzten Yiertel des Untersclienkels entspringt. Die AusdelmuDg 

 des Ursprunges variirt jedocli ungemein. 



" Insertion. Der Muskel gelit in eine starke, rundliche Sehne 

 iiber, welche am aussereu Malleolus durch ein Retinaculum 2^6ronei 

 tritt und sich dann an der proximalen Ecke des mittleren oder 

 hintersten der drei Tarso-Metatarsalknochen inserirt." 



Note. — These remarks are here added on June 25, 1889, and in 

 concluding I would say that the muscle certainly has an extensive 

 fibular attachment in Corvus, and although it may eventually 

 prove to be a peroneus muscle, I was in no ways influenced in 

 naming it by any semblance it might have to that muscle so called 

 in Homo, but rather by the fact that a tibialis posticus occurs in 

 certain reptilian forms. — R. W. S. 



^ This muscle has the following account of its synonymy given by 

 Professor Gadow : — 



" 52a. M. FLEXOR PERFORANS ET PERFORATUS DIGITI IL 



M. fertius j)osterioT circum tibiam et fibidam. Steno. 



