448 STRUCTURE AND CLASSIFICATION OF BIRDS 



biceps, which appears to end on the fascia of the wing.^ 

 The expansor secundariorum, found only among the 

 Oceanitidse, is pecuhar in that it arises from the surface of 

 the pectoral ; its muscular belly is, as usual, at the elbow, 

 and the tendon is joined by a branch from the scapularies. 

 The anconmus has a well-marked tendinous attachment to 

 the humerus. 



The muscles of the hind limb, to which Gaerod attached 

 so much classificatory importance, vary much in the group. 

 The ambieiis is present in all except Fregetta and Pele- 

 canoides. In Garrodia and some others the tendon does 

 not cross the knee.'' All have a femorocaudal, but the 

 accessory is absent in Bulweria and Pelecanoides. The 

 semitendinosus has an accessory in the OceanitidaB, but not 

 in the others. It is inserted separately from the semi- 

 membranosus. The deep flexors blend about halfway down 

 the leg ; but when a hallux is present it receives no slip 

 from the conjoined tendons. The syrinx of the Tubinares 

 shows an interesting series of gradations, from a quite 

 ordinary tracheo-bronchial type to what is very much like the 

 bronchial syrinx of the Caprimulgidse, though Furbeinger, 

 while admitting the ' bronchophone tendency ' of the syrinx 

 of the Strigidae, as a point of similarity between that group 

 and the Caprimulgidse, considers that only ' artificially ' can 

 the Tubinares and the Spheniscidse be brought into the same 

 line. Nevertheless in the series of Tubinares the bronchial 

 rings to which the intrinsic' muscles are attached seem to 

 move further down. Forbes, however, regards this as a 

 splitting of the trachea, and holds that the intrinsic muscles 

 are invariably fastened to the fifth semi-ring. ' It is in the 

 genus Pelecanoides,' remarks Forbes, ' that the typical 

 construction of the syrinx of the Tubinares is seen in its 

 simplest form.' In this bird all the bronchial rings are 

 semi-rings, and there is a three-way piece of the. usual 



' In a specimen oQNycticorax griseus on one side of the body I found a 

 tendon from the biceps runninglto the tensor brevis tendon, which may be com- 

 parable to the above-described slip. 



' C£. as to this Opisthoconws,. CEdicnemus, and Casuarms. 



