654 



DK. P. CHALMERS MITCHELL ON THE 



D. 



modification in one direction of the Eurypyga type its peculiarity 

 is that the divisions of the ballucis tendon for the digits unite with 

 the similar divisions of the profundus tendon only very dose to 

 the insertions. The conditions in the other members of t he 

 Grruiformes, as will be apparent without description from the 

 drawings in text-fig. 85, can easily be explained as apocentric modi- 

 fications in a different direction, consisting in further specialization 



Text-fig. 85. 



Deep plantar tendons of Gruiformes. 



I. Ballus and Psophia. 

 . Otis. VI. Bhinoehetvs. 



IT. Balearica. 111. Arwmut. IV. Cariama. 

 VII. Eurypyga, \ J T I . Heli&rnis. 



The hallux in all is to the left : the arabic numerals represent the digits : 

 the flexor longus ballucis is in white ; the flexor perforana Ben profundus 

 is deeply shaded. 



of the ballucis tendon and withdrawal from supply to the digits 

 other than the hallux. The vinculum seen in the case of RcdJvs 

 and Psophia (text-fig. 85, 1). and which is found in a large number 

 of birds, appears to be a late stage in the withdrawal of the hallucia 

 tendon from the other digits, and not, as it often lias been regarded, 

 as a simple condition. It is plain, however, that these junctions 

 show in the same fashion as many of the other structures I have 

 passed in review, that while there is a general similarity among 

 the members of the f-rruiform assemblage, there is little close 

 coherence in the group. 



