AVES. 



295 



along the edge of the aponeurotic expansion 

 of the wing. In this situation it acquires 

 exactly the structure and elasticity of the liga- 

 mentum subflavum or ligamentum nuchae ; it 

 then resumes its ordinary tendinous structure, 

 passes over the end of the radius, and is in- 

 serted into the style of the metacarpal bone. 

 It combines with the preceding muscle in 

 bending the fore-arm; and further, in conse- 

 quence of the elasticity of its tendon, puckers 

 up the soft part of the fold of the wing. (See 

 48, y?g. 133.) An analogous structure is met 

 with in the wing of the bat. 



A lesser flexor of the fore-arm, and stretcher 

 of the alar membrane (31) arises, as a portion 

 of the serratus magnus from the ribs, and ter- 

 minates in an aponeurosis inserted into the alar 

 membrane and fascia of the fore-arm ; it is re- 

 presented in the figure as turned aside. 



The Extensor metacarpi radialis longus (32) 

 is the first muscle which detaches itself from 

 the external condyle of the humerus (E), and it 

 forms the radial border of the muscular mass of 

 the fore-arm ; it terminates in a large tendon 

 about the middle of the fore-arm, and this 

 tendon passes along a groove of the radius, over 

 the carpus, to the phalanx of the so called 

 thumb, or spurious wing, into the radial margin 

 of which it is inserted. It raises the hand, 

 draws it forwards towards the radial margin of 

 the fore-arm, and retains it in the same plane. 

 In the Penguin this muscle is extremely feeble, 

 and the tendon is lost in that of the tensor plicae 

 alar is. 



The Extensor metacarpi radialis brevis (33) 

 arises below the preceding from the ulnar edge 

 of the radius, and is inserted into the phalanx 

 of the thumb immediately beyond the tendon 

 of the preceding muscle. The two tendons are 

 quite distinct from one another in the Birds of 

 Prey, the Ostrich and Parrots, but unite at 

 the lower end of the fore-arm in the Anatidte, 

 Phasianida, and Gruida. 



The muscle analogous to the Extensor carpi 

 ulnaris (34) comes off from the inferior extre- 

 mity of the outer condyle of the humerus, 

 passes along the middle of the exterior surface 

 of the fore-arm, and its tendon, after passing 

 through a pulley at the distal end of the ulna, 

 is inserted into the ulnar phalanx. It draws 

 the hand towards the ulnar edge of the fore- 

 arm, and is the principal abductor or folder of 

 the pinion. 



The Flexor metacarpi radialis (35) is a short 

 and weak muscle, which arises from the inferior 

 part of the ulna, descends along the internal 

 side of that bone, winds round its lower extre- 

 mity and the radial edge of the carpus, passes 

 beneath the tendon of the radial extensors, and 

 is inserted, external to the latter, high up into 

 the dorsal aspect of the radial phalanx of the 

 metacarpus. In the Ostrich it arises from the 

 lower third of the ulna. In the Penguin it is 

 wanting. 



The Flexor metacarpi ulnaris (36) arises 

 beneath the fore-arm from the internal pulley 

 of the ulna, continues fleshy to the pinion, and 

 is inserted, first into the ulnar carpal bone, then 



into the ulnar phalanx. The latter insertion is 

 wanting both in the Ostrich and Penguin. 



The muscles of the pinion or hand are few, 

 and very distinct from one another; the thumb 

 or spurious wing is moved by four small mus- 

 cles, viz. two extensors, an abductor, which 

 draws the thumb forwards, and an adductor. 

 The second digit receives three short muscles, 

 two of which are extensors, and the third an 

 abductor, in this action it is aided by one and 

 opposed by another of the extensors. The 

 lesser digit receives an abductor, which comes 

 from the ulnar edge of the preceding phalanx. 



Muscles of the lower extremity. Notwith- 

 standing the simplicity of the motions of the 

 lower or posterior extremity, the muscles of 

 this part are numerous, and present several 

 peculiarities in birds. The femur can be moved 

 freely forward and backward, but its rotation is 

 limited by a strong ligamentum teres, and the 

 structure of the hip-joint does not permit it to 

 be carried under the body, or far outwards. 



In consequence of the form of the pelvis, 

 the psoas magnus and parvus, the obturator 

 externus and the quadratus lurnborum do not 

 exist in birds. 



A large muscle, regarded by Cuvier as the 

 Obturator internus, takes its origin from the 

 internal surface of the ischio-pubic bone, it is 

 directed from behind forwards, and gives off a 

 strong and long tendon which passes through 

 the small opening at the anterior part of the 

 obturator foramen, which is situated between 

 the pubis and ischium, (f, jig. 131.) In this 

 situation a muscle, arising from the external 

 border of the opening, attaches itself to 

 the preceding, and is inserted conjointly with 

 it into the posterior and outer aspect of the 

 trochanter. Meckel compares this muscle with 

 the pectineus, especially as it exists in the Sau- 

 rian Reptiles, but observes that as it arises 

 from both the internal and external surfaces of 

 the circumference of the obturator foramen, it 

 may represent both the internal and external 

 obturator muscles. It is of an extraordinary 

 size in the Ostrich. 



The femur is raised by three muscles. 



The most superficial and highest of these 

 elevators (37) arises by a broad and thin aponeu- 

 rosis from the anterior and external surface of 

 the ilium, it is of a square form, descends al- 

 most in a straight line, and is inserted into the 

 posterior part of the trochanter. Meckel re- 

 gards it as analogous to the Glutteus medius: 

 Carus calls it the Glutaus maximus. But the 

 latter, according to Meckel, is represented by 

 the posterior part of what Carus terms the 

 RectusJ'emoris latissimus (40). 



Anterior to the Glut&us medius of Meckel, 

 there is a much smaller muscle, which extends 

 from the anterior margin of the ilium to the 

 trochanter, where it is inserted in front of the 

 preceding. It is of an elongated quadrilateral 

 form, and it represents the Glut&us minor of 

 quadrupeds. It is wanting in many of the 

 Natatores, and arrives at its greatest degree of 

 development in the Raptorial Order. 



A third muscle, still smaller and longer than 



