of the Leg of the Ostrich. 267 



iliacus, and glutseus medius, as shown in fig. I., and is inserted 

 in the anterior ridge at the base of the great trochanter^ with 

 the M. glutseus minimus (fig. II.), with the fibres of which it is 

 connected. It weighs If oz. 



20. M. obturator. In the Ostrich, as in most birds, the 

 internal and external obturator muscles are united, arising from 

 both the inside and the outside of the bony circumference of the 

 obturator foramen, and from both sides of the obturator mem- 

 brane ; their common tendon passes through the lesser ischiadic 

 notch, which forms a pulley, changing the direction of the force 

 through 90°, and receives, on emerging from the notch, the 

 fibres of the little gemelli (fig. I.), placed at each side, anterior and 

 posterior, to guide the obturator tendon to its insertion (fig. II.) 

 on the outer part of the top of the femur. It weighs \7\ oz. 



21, 22. MM. gemelli weigh i oz. 



23. M. coraco-clavicularis. In the wing of the Ostrich there 

 is a very remarkable muscle, which arises from the bony margin 

 of the coraco-clavicular foramen. This foramen corresponds, in 

 the upper extremity, with the ischiado-pubic or obturator foramen 

 of the lower extremity ; and this muscle, passing under a strap- 

 ligament on the shoulder, to be inserted in the outer part of the 

 great tuberosity of the humerus, corresponds with the obturator 

 muscle of the leg. 



I consider this muscle to be the second pectoral of ordinary 

 birds, and to be the proper levator humeri. It is usually placed 

 between the first and third pectorals, on the sternum, and lifts 

 the wing by means of a pulley which changes its direction 

 through 135°. This contrivance is necessary in birds of flight, 

 in which it is of as much importance to stow the weight aft as 

 it is in ships to place the fore mast well forward ; but as the 

 Ostrich is a running bird, the Divine Contriver has left his 

 second pectoral to lift the humerus by a direct pull, without 

 expending any ingenuity on pulleys to change its direction, as is 

 absolutely necessary in birds of powerful flight, such as the Fal- 

 con, in which the pulley of the second pectoral is as remarkable 

 a contrivance as the pulley of the obturator muscle in the Ostrich. 



In fact, throughout the whole range of the muscular mechanism 

 of various animals, every pulley changing the direction of an 

 original force presents a problem to be solved, and tells of a 

 Contriving Mind, which has deviated, for some purpose discover- 

 able by us, from the simple contrivance of muscular fibres pull- 

 ing directly from their origin to their insertion. 



24. M. gastrocnemido-solseus. This great muscle has four 

 distinct heads : — (a) from the outer side of the patella and of 

 the ligamentum patellae j {b) from the external condyle of the 

 femur (fig. II.) ; (c) from the condyloid pit of the inner condyle. 



