SOME POINTS IN THE ANATOMY OF STEATORNIS. 185 
Steatornis has two carotid arteries, as have both the Strigide and . 
Caprimulgide. 
With regard to the myology of this bird, the only muscles which 
will be considered are those which have been found to have some 
bearing on the systematic position of birds generally. 
In the thigh, the ambiens (Sundevall)—the slender muscle which 
_ in many birds runs from the innominate bone, just above the aceta- 
bulum, along the inner side of the thigh to the knee, which it crosses 
obliquely in the fibrous capsule below the patella, and then blends 
with the flexor perforatus digitoram—is absent, as it is in the Strigide 
and Caprimulgide. 
The semitendinosus, the outer of the two muscles which form the 
lower fold of the thigh (the semimembranosus being the inner), and 
which runs from the region of the lower end of the innominate bone 
to the tibia, is present, as in the Caprimulgide, it being quite absent 
in all the Strigide. As in the Caprimulgide also, this muscle receives 
A Fig. 4. B 
Muscles at the outer side ide of the elbow ; A, of right wing of Caprimulgus europaeus ; 
B, of left wing of Steatornis. 
tpb, tensor patagii brevis; eer, extensor carpi radialis; 6, biceps; d, deltoid ; 
#, triceps ; &, humerus. 
an accessory head from the lower end of the femur, which helps te 
send a partial insertion of the muscle down the leg. 
The femoro-caudal (which runs as @ narrow muscular ribbon from 
the middle of the linea aspera of the femur to the coccyx, covered by 
the semitendinosus and crossed superficially by the sciatic artery and 
nerve) is quite absent ; it is well developed in the Caprimulgid, small 
in the Strigide, and absent in very few birds. 
In the upper limb the second pectoral (subclavius of Rolleston) is 
not large, extending about halfway down the sternum, as it does in Page 534. 
