472 Johnson, A Four-winged Wild Duck. [ G ct. 



elbow joint, and somewhat beyond the proximal half of the humerus, 

 passes over into another bony process, similar to the first men- 

 tioned but longer, measuring about 18 mm. in total length. This 

 process terminates in an enlarged headlike end, which, in life, was 

 anchylosed on its lateral side to the median epicondylar region of 

 the humerus of the primary wing by a rather narrow, low ridge of 

 bone. The ligament, near its proximal end has a loop which evi- 

 dently has resulted from tension exerted by the nerves to the biceps 

 muscle, which lie in this loop. The median nerve passes distally 

 between the ligament and the shaft of the humerus. The parts 

 described, it will thus be seen, represent the imperfectly developed 

 humerus of the left secondary or accessory wing. 



On the right side, the humerus of the primary wing is somewhat 

 stouter than that on the left. At about the middle of the shaft 

 (Fig. 3) on its inner aspect, there becomes evident a rather narrow, 

 rounded ridge of bone which further distally differentiates into a 

 slender cylindrical shaft, terminating in an enlarged end similar to 

 that of the left side, and anchylosed to the median epicondylar 

 region of the primary humerus. This represents the humerus of 

 the right accessory wing. At only one place does this shaft become 

 entirely free from the primary humerus; here a narrow foramen is 

 formed, about 6 mm. in length, transmitting a branch of the 

 Nervus brachialis longus inferior. 



The forearm skeleton is represented by a single bone. The 

 general shape and articular relations are those of a radius rather 

 than an ulna. It is set at an angle of about thirty-three and a 

 third degrees with the corresponding humeral element, with the 

 distal end of which it is firmly anchylosed. The bone measures 

 43 mm. in length, as compared with 50 mm. of the radius of the 

 primary wing, and is approximately of the same diameter as the 

 latter. The corresponding bone of the right side is practically 

 identical in size and shape but is anchylosed at right angles to the 

 upperarm segment. The exact relations of the left forearm bone 

 to the primary humerus have been destroyed by the shot wound, 

 but its lateral surface shows that an anchylosis has existed similar 

 to that of the right side. The principal difference is that the left 

 forearm bone forms a sharper angle with the two humeri. On the 

 right side where the elbow articulations are intact, the accessory 



