362 STRUCTURE AM) CLASSIFICATION OF BIRDS 



muscles and reach ulna, but they cross it as a single diffuse 

 band formed by their fusion. 



Ceratorhina inonocerata has a slight patagial fan, as well 

 as ulnar slip ; otherwise it is like the last. 



Fratercula arctica has only two brevis tendons, upon the 

 anterior of which, at the origin of the patagial fan, is an 

 ossicle. 



The biceps slip is present in Alcidse, but is generally, if 

 not always, peculiar. Thus in Alca torda it is inserted partly 

 on to patagial membrane, partly on to inner of two brevis 

 tendons (not long us tendon). 



In Lunda cirrliata it arises tendinously and joins inner 

 of three patagialis brevis tendons. The biceps slip (as in 

 some petrels) is all that is left of the humeral head of the 

 biceps. 



The biceps slip of Fratercula arctica is inserted on to 

 middle of three tendons. 



]n Brachyrhamphus marmoratus the biceps slip ends in 

 a long and fine tendinous thread, which is inserted on to the 

 innermost of the three tendons of the brevis. 



In Plialeris psittacida the biceps slip is firmly adherent 

 to the single brevis tendon ; but from it just at the lower end 

 of the line of the brevis tendon an obliquely running strand 

 is found, which reaches the tendon of the longus. 



The biceps, as already mentioned, consists merely of the 

 coracoidal head, the humeral head being represented only by 

 the biceps slip. 



The muscle is not large, and in Plialcris its muscular 

 belly is largely divided into two. 



The humeral head of the anconceus seems to be nearly 

 always present. 1 



There is no expansor secundarioruin. The deltoid has, 

 as a rule, no scapular slip, but there is one in Uria. 



The muscles of the leg which are invariably present are 

 the femoro-caudal and the seinit<'iulinoxnx. The accessory 

 head of the latter is never present. The ambiens and the 

 accessory femoro-caudal may be present, and, except in 



1 It is (? individually) absent in Brachyrliamplius marmcratus. 



