1873.] 



ANATOMY OF STEATORNIS. 



533 



attached to the middle of the first fully developed half ring The 

 depressor muscles of the trachea are independent of these. 



Steatornis has two carotid arteries, as have both the Strigida; 

 and Caprimulgidae. ° 



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 digitorum— is absent, as it is in 

 the btrigidse and Caprimulgidee. 



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 Caprimulgidae, it being quite absent 

 m all the Stngidae. As in the Caprimulgidae also, this muscle 



Fig. 4. 



Muscles at the outer side of the elbow : a, of right wing of Cawimulqus 

 europaius; b, of left wing of Steatornis. 



tpb, tensor patagii brevis; ecr, extensor carpi radialis ; b, biceps; d, deltoid- 



t, triceps ; h, humerus. 



receives an accessory head from the lower end of the femur, which 

 helps to send a partial insertion of the muscle down the leg. 



The femoro-caudal (which runs as a narrow muscular ribbon from 

 the middle of the hnea aspera of the femur to the coccyx, covered 

 by the semitendinosus and crossed superficially by the sciatic arterv 

 and nerve) is quite absent ; it is well developed in the Caprimul- 

 gidae, small in the Strigidae, 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 



