82 STRUCTUEE AND CLASSIFICATION OF BIRDS 



It has generally a broadish insertion on to the scapula, but 

 in Meiglyptes, many Passeres, &c., it is attached merely to the 

 extremity of that bone. The pars metapatagialis is absent 

 in ratites (except ^4^ ^er^/a;), hummingbirds, and a few others. 

 It springs from 1-4 ribs, and is inserted on to the meta- 

 patagium. 



Serratus Profundus. — This muscle is highly developed 

 in Struthio and Gasuarius, less so in other struthious birds 

 and in the Carinates. It arises from a variable number of 

 cervical and dorsal ribs, and it passes bacWards (in the 

 contrary direction, therefore, to the serratus superficialis) to 

 be inserted on to the scapula. 



T?atagiaUs} — This muscle, concerned with the folding of 

 the patagial membrane, is present in all birds except the 

 struthious. It arises from the clavicle and from the tip of 

 the scapula, is sometimes divided into two muscles from the 

 start, and sometimes arises as a single muscle, which 

 immediately divides into two tendons, the tensor patagS 

 longus and the tensor patagii brevis. Exceptionally the 

 former may be absent. In a specimen of Crex pratensis 

 the representative of tensor patagii longus was found by 

 GrAREOD to be simply the biceps slip, a muscle that will be 

 treated of presently. The size and- importance of this 

 muscle vary considerably ; it is largest in the parrots, 

 where, indeed, it is uncertain whether a part of the deltoid 

 has not been converted to a similar function. This matter, 

 however, is dealt with under the description of that family. 

 The tensor patagii longus always ends in a single tendon 

 which runs along the anterior margin of the patagium and is 

 inserted on to the metacarpal. It is usual for the middle 

 part of this tendon to be of a more fibroid character and of 

 a yellowish colour, contrasting with the steely and typically 

 tendinous aspect of the other tendons arising from the 

 tensores. Very commonly the entire tensor muscle is 

 reinforced by a tendinous or muscular slip from the pecto^ 

 ralis, and sometimes there is a separate slip to each of the 



' G. Bdohet, ' Premiere Note suv I'Appareil Tenseur,' &o., C. B. Soc. Biol. 

 1888, p. 328. 



