MUSCLES OF THE FOEE LIMB 83 



two tensores. It is also very general for one of the two 

 tendons, or for both before their division, to be attached by a 

 tendinous slip to the deltoid crest of the humerus. The 

 tensores patagii are of considerable use in classification. 

 But it must be admitted that they are apt to vary greatly 

 from genus to genus. The variations chiefly concern the 

 more or less complicated condition of the tendons of the 

 brevis. The simplest condition is seen, e.g., in Bham^hastos 

 Cuvieri, where the tendon is single and is attached below to 

 the tendon of origin of the extensor metacarpi radialis. 



A further degree of compHcation is seen in, e.g., a cuckoo, 

 where the single tendon gives off, near to the fore arm, a slip 

 running obliquely wristwards, which is attached to the tendon 

 of the extensor metacarpi radialis. In the limicolous birds the 

 main tendon is usually divided from the first into two, of 

 which the anterior has the wristward slip, already referred 

 to ; in those birds and many others there is the further 

 complication of a band of tendinous fibres which arise at the 

 junction of the wristward shp with the fore arm, and pass 

 obUquely forwards and upwards to be inserted on to the 

 tendon of the longus. This slip is termed, in the following 

 pages, the ' patagial fan ; ' it is frequently of a fanhke form. 

 The tendon of the tensor patagii brevis has riot always the 

 regular form that it has in the t3^es that have been already 

 selected for illustration. In the tinamou, Bhynchotus, for 

 instance, the tendon is a diffuse fascia spreading out over 

 the greater part of the patagial membrane ; in other birds, 

 e.g. storks, it is a broad, rather diffuse band, as a rule with 

 a thicker edge or edges. A pecuUar condition of the 

 tendons of the brevis characterises the auks, some gulls, and 

 at least one limicolous bird. In them (see below) one or 

 two delicate tendons arise from the longus tendon near to 

 the insertion thereon of the patagial fan, and run obUquely 

 backwards and downwards to be attached on to the dorsal 

 surface of the fore arm — the reverse side, that is to say, to 

 that to which the other tendons which together make up 

 the tensor patagii brevis are attached. 



In some birds, e.g. certain passerines, the tendon of the 



