326 STRUCTURE AND CLASSIFICATION OF BIRDS 



The deep flexor tendons of Heliornis are remarkable (see 

 fig. 160) for the fact that both tendons spht into three branches 

 for the three digits before they unite, the shp to the hallux 

 being given off from the flexor hallucis previously. The 

 conditions which characterise Podica are unknown. In the 

 fore hmb some of the muscles are characteristic, and differ 

 from those of the rails. The patagialis brevis consists in 



Fig. 160. — Deep Flexoe Tendons 

 OF Heliornis (after Beddaed). 



A, fl. hallucis ; 5, fl. communis ; 1-4, 

 slips to digits. 



Fig. 161. — Patagial Muscles of 

 Heliornis (after Beddaed) 



Tp, tensor patagii ; Bi, biceps : Bi.Sy 

 biceps slip : 37, tendinous slip. 



both of a simple undivided tendon, which has not more than 

 an indication of a patagial fan. This indication is seen only 

 in Heliornis (fig. 161) in the shape of an upwardly directed 

 tendinous slip, to which, a .little before its termination — 

 apparently upon the patagium — a well-developed biceps slip 

 is attached. In Podica the biceps slip ends freely upon the 

 patagium. Both these conditions are different from what is 

 met with in the rails, but are to some extent paralleled 

 among the grebes. In Podiceps the biceps slip ends freely 

 upon the patagium, as in Podica. In Mchmophorus (p. 387) 

 the biceps slip is connected directly with the patagial fan. 

 The likeness between that bird and Heliornis appears to me 

 to be unmistakable. 



The expansor secundariorum is present, and the anconeus 



