1873.] 



CERTAIN MUSCLES OF BIRDS. 



643 



The Struthiones present marked peculiarities. 



In Apteryx the postacetabular portion of the tensor fasciae is very 

 large, and slightly overlapped at the lowest point of its origin by the 

 posterior superior portion of the semitendinosus. The semitendinosus 

 is well developed, and has a broad accessory head. The accessory 

 femoro-caudal is peculiar ; for, on removing the biceps cruris, its su- 



Fig. 6. 



Outer view of thigh of Apteryx owenii, dissected. 



s, sartorius; t f, tensor fasciae; bo and bi, biceps, origin and insertion; gl, i 

 and it, gluteus primus and quartus ; st, semitendinosus ; ast, accessory 

 semitendinosus; sm, semimembranosus; sfc, superficial femoro-caudal; 

 fc, femoro-caudal ; afe, accessory femoro-caudal ; Ad, adductor. The 

 asterisk on the semimembranosus is on the spot at which its second or true 

 insertion is ; the other asterisk is placed on the slip of the accessory femoro- 

 caudal (in this case specially modified), which is found in Struthious birds 

 and the Tinamous only, above the sciatic vessel and nerve. 



perficial portion is seen running obliquely upwards and forwards to 

 the whole length of the linea aspera of the femur, from its usual 

 origin. The sciatic artery and nerve are superficial to this muscle 

 (adductor longus of Owen), and parallel to its insertion, as in most 

 birds ; but they, as is not the case except in the Struthiones and 

 Crypturi, perforate it at the sciatic notch, leaving a small portion of 

 the muscle (the adductor brevis of Owen) above them. The anterior 



41* 



