(544 MR. GARROD ON CERTAIN MUSCLES OF BIRDS. [June 17, 



terminal fibres of this muscle are situated external or superficial to 

 the accessory semitendinosus. 



After this muscle has been removed or turned back, there is seen 

 a deeper muscle, which, if the one described above did not exist, 

 would be justly considered to be the true femoro-caudal and the ac- 

 cessory femoro-caudal, part springing from the iliac ridge and part 

 from the coccyx, whilst both are inserted into the posterior portion 

 of the linea aspera and have the nerve to the semimembranosus 

 situated between them and the adductor magnus. 



The semimembranosus is also peculiar in having a second head of 

 origin from the ischium, behind the femoro caudal, and just in front 

 of the origin of the semitendinosus, so that the femoro-caudal runs 

 partly in a separate canal between the two heads of origin of this 

 muscle and covered by it. 



The other muscles are present as in most birds. The ambiens is 

 strong. 



Species examined. 



Apteryx owenni. Apteryx mantelli. 



In Casuarivs the postacetabular portion of the tensor fasciae is 

 very large, and is overlapped below and behind by the semitendinosus 

 near its origin ; the femoro-caudal forms a small cylindroidal belly, 

 which is continued upwards as a narrow tendon ; the accessory femoro- 

 caudal is enormous, being perforated by the sciatic artery and nerve ; 

 it replaces to a great extent the obturator externus, which is peculiarly 

 small and situated anterior to it in origin, as usual. The semiten- 

 dinosus is present and has a broad accessory head. The ambiens is 

 absent. The other muscles are as in most birds. 



Species examined. 



Casuarius bennettii. Casuarius bicarunculatus. 

 galeatus. 



In Dromeeus novee-hollandiee the semitendinosus is larger than in 

 Casuarius, and the accessory head is large ; the femoro-caudal is ab- 

 sent ; and the accessory femoro-caudal is very large, being pierced by 

 the sciatic artery and nerve. The biceps cruris is very peculiar in 

 not being inserted in its usual characteristic manner, but ending a 

 little anterior to the middle of the thigh very indefinitely, blending 

 with the fasciae in that region, and not being continued directly to 

 the fibula at all. The semimembranosus also is peculiar in having 

 an aponeurotic connexion with the middle of the linea aspera, from 

 about the middle of its course. The ambiens is absent. 



In Rhea americana a somewhat similar condition is found. The 

 biceps is normal ; and the semitendinosus, the accessory semiten- 

 dinosus, as well as the postacetabular portion of the tensor fasciae are 

 much as in Casuarius and Dromeeus. The femoro-caudal is absent ; 

 the accessory femoro-caudal is large, being perforated by. the sciatic 

 artery and nerve ; and the ambiens is strong. 



In Struthio camelus the ambiens is also well developed. 



