ON CERTAIN MUSCLES OF BIRDS. 207 
deeper muscle, which, if the one described above did not exist, would 
be justly considered to be the femoro-caudal and the accessory 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-candal 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. 
Apteryz owenit. Apteryz mantelli. 
In Casuarius the postacetabular portion of the tensor fascie is very 
large, and is overlapped below and behind by the semitendinosus near 
its origin; the femoral-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 pecu- 
liarly small, and situated anterior to it in origin, as usual. The semi- 
tendinosus 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 Dromeus nove-hollandie the semitendinosus is larger than in 
Casuarius, and the accessory head is large; the femoro-candal is 
absent; 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 fascie in that region, and not being continued directly to 
the fibula at all. The semimembranosus also is peculiar in having 
an aponeurotic connection 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 fasciz are © 
much as in Casuarius and Dromeus. The femoro-caudal is absent; 
