16 Mr. W. A. Forbes on the late Professor Garrod's 



VI. The Method of Insertion of the Tensor patagii brevis 

 Muscle. 



In the patagial membrane of the wing in most birds there 

 are two muscles present, the fleshy bellies of which arise chiefly 

 from the scapular extremity of the furcula, whilst their tendons 

 run between the two layers of membrane of which thepatagium 

 is composed. These muscles are the tensor patagii longus and 

 the tensor patagii brevis. Arising in common, or in close 

 proximity to each other, the tendon of the tensor patagii 

 longus forms the more or less stiff'ened, though flexible, ante- 

 rior border of the patagium ; the tendon of the shorter of the 

 two muscles runs more or less parallel with the humerus, 

 ending near the elbow-joint. In difiierent birds its insertion 

 takes place in different ways, the tendon in some cases simply 

 running straight on to the ulnar side, and there becoming 

 blended with the general fascia of the part, whilst in others 

 it becomes united, more or less intimately, with the tendi- 

 nous origin, springing from a tubercle on the humerus, 

 of a muscle lying on the radial side, the extensor meta- 

 carpi radialis longior. In some cases additional slips from 

 the main tendon are given ofi", the arrangement sometimes thus 

 getting very complicated {e. g., in the Trogonidse) . As a 

 rule, every natural family of birds has a characteristic arrange- 

 ment of these tendons ; so that their disposition often aff'ords 

 great help in classification. This is the case, for example, in 

 the Passeres ; throughout the whole of that immense group 

 one arrangement, only slightly masked in one or two aberrant 

 forms, which can be easily recognized and is most charac- 

 teristic, obtains. The same is the case with the very closely 

 allied groups of Picidae, Ramphastidse, Capitonidae, and Indi- 

 catoridse. These points were first worked out by Prof. 

 Garrod in the first of his papers on Passerine birds*; and the 

 arrangements in nearly all the fam;ilies of his "Anomalo- 

 gonatous birds " are there described and in several cases 

 figured. In the Homalogonatee, too, they off"er nearly as 

 well-marked peculiarities, though, unfortunately, his purpose 



• P.Z.S. 1876, pp. 506-512, pis. xlviii.-li. 



