MUSCLES OF THE HIND LIMB 95 



in others. There is also occasionally {e.g.. hornbills) an 

 additional attachment to the gastrocnemius. 



Amhiens. — This muscle, as is well known, is not present 

 in all birds. Though the late Mr. Gareod used it largely 

 in his scheme of classification, its mere presence or absence 

 is not an absolute guide to the systematic rank of the bird. 

 Broadly speaking, it is present in all the birds which 

 G-AEEOD called homalogonatous, or normal-kneed, and 



Femur 



Fig. 52. — Leg Muscles or Balearica (AriEE Mitchell). The 



Ambiens Tendon is out. 



1, flexor longus hallucis ; 2-4, flexores perforati ; 2', 3' flexores perforati et perforantes. 



it is absent in all the birds which were termed by him 

 anomalogonatous, or abnormal-kneed. But there are excep- 

 tions, at any rate on one side. Thus while the muscle is 

 present in the storks generally it is absent from the nearly 

 related herons, and, indeed, is absent in three storks, Xeno- 

 rhynchus, Abdimia, and Dissura, When the muscle is 

 present it has as a rule the relations described above ; but 

 in a few birds it does not reach beyond the knee, thus 

 showing, perhaps, an incipient disappearance. The import- 



