763 



and again on the left as far as the claricle, coracoid, and epicoracoid 

 are concerned, but not in its scapular portion (see figure 3;. The scapula 

 on this side, although fairly normal in shape and taking the usual part 

 in the formation of the glenoid cavity, is articulated with the coracoid 

 and clavicle in such a manner that it runs in a posterior direction at an 

 angle of about 30" to that normally taken. Closely attached to its 

 anterior dorsal edge is another somewhat reduced scapula belonging 

 to the supernumary limb, for the articulation of which it offers an in- 

 complete shallow glenoid cavity. The extra scapula is somewhat similar 

 in shape to that of the right side but entirely different in orientation. 

 Instead of the supra scapula being attached to the dorsal end of the 

 scapula it is attached to its ventral side a little way from the end and 

 runs forward beneath the extra scapula at an angle of about 110" to 

 the normal angle between the two bones. Thus the scapula comes to 

 lie in an antero-posterior direction at an angle of about 90° to the 

 position it usually occupies. The humerus of the supernumary limb 

 although small is fairly normal, showing distinct deltoid and condylar 

 ridges, a head for articulation with the glenoid cavity and an articulat- 

 ing surface for the radio-ulna. The radio-ulna is bent in an unusual 

 way and has a broken end which suggests that the distal extremity was 

 removed while the skeleton w^as still cartilagenous. The bones of the 

 left arm are quite normal. 



Specimen B. Rana temporaria. 



In this specimen the supernumary arm was on the right side and 

 was situated slightly dorsal and posterior to the normal arm. It was 

 thin, ending at its distal extremity in a blunt point representing a single 

 digit and although an arm and fore arm could be recognised the joints 

 did not appear to be capable of movement. The whole limb was covered 

 by skin in a normal manner and was very similar in appearance to that 

 of Specimen A. 



Again as in the preceeding example no part of thepectoralis muscles 

 was connected with the extra arm. The musculature of this arm was 

 largely composed of much reduced muscles approximately corresponding 

 to the Aconaeus, Dorsalis scapulae, Latissimus dorsi, Deltoideus, 

 Flexor carpi, Extensor carpi and Palmaris longus Gaupp (6j of the 

 normal frog. 



The second spinal nerve in addition to supplying the right arm gave 

 off a large branch to the supernumary one. 



On either side of this nerve ran a blood vessel, one coming from 

 the sub-clavian artery near the origin of the coraco-clavicularis artery, 

 supplying the arm and the other returning the blood to the brachial vein. 



