146 



ON THE ANATOMY OF THE CONDOR. 



[Mar. 18, 



The additional muscular and tendinous slips which have heen 

 described in this paper as uniting the valve-margin with the parietes 

 in certain birds are comparable to the additional muscles which tie 

 down the valve in the Monotremata, and, as has been pointed out. 

 they are traceable in the Crocodile heart. 



2. Trachea. 



The trachea of the American Vultures (including, of course Sar- 

 corhamphts) has been long known to differ greatlj' from that of 

 other Accij)itres in having no intrinsic muscles, and in showing no 

 definite modification in the directiou of the formation of a syrinx. 



Fig. 3. 



Syrius of Condor (nat. size). 



ce, opsophngus ; rn. muscles enveloping extremity of bi-onchia ; TV, trachea ; 

 (I, ostia ; s. septum dividing prebroncbial from anterior intermediate 

 iiir-sae : up. septum between anterior and posterior intermediate air-sac. 



In all three genera the bifurcation of the trachea is very similar : 

 but on the whole Sarcorhamphus comes nearer to Gypagus than 

 either of them do to Cathartes. This is principally shown in the 

 comparative thickness of the rings at the point of bifurcation ; these 

 are extraordinarily thin in Cat/iartes, leaving therefore large membra- 

 nous spaces. The bifurcation of the trachea in Cathartes is especially 

 Lacertilian. The rings of the bronchi iu Sarcorhamphus cease for 

 some time before the bronchi enter the lungs; this fibrous portion 

 (see woodcut fig. 3) is closely enveloped by a mass of muscle (m). 

 The function of this muscle must be much the saiue as that of the 

 intrinsic muscles of the syrinx in those forms which are furnished with 



